Does anyone have any pain medication mangement advice for a senior who has hurt her back?

I was adopted at 2 and now I am 45 . Since I was 30 I have been caring for my parents 10 years devoted to my father who smoked and had a long list of problems (heart, lung and kidneys) He made it to 79 and died of a heart attack. My mother who was 10 years older than my father from the start is now 99 she was always healthy. She started having dementia/alzheimers 2010-11 the meds the doctor put her on were to strong so I cut it in half that worked good for 6-8 months and she started having really loose stool again and that far away druged out look so I took her off it all together. Some people tried to tell me that maybe she is just old and having some memory problems due to old age. But I took her to see the doctor anyway. It has been almost a year since she took the meds and she is fine just like she was before taking the meds. She still calls the tv a mirror and things like that but she is no worse and she is not sick at her tummy & loose bowels anymore. She talks with me like she used too, before she would just set there . Not like my mom at all. She is flower crazy loves working in the yard and now she is back out there and I am so glad for her. We try to plant a new one every week, although I'm the one doing most of the work. She picks were to put it, she picks the plant at the store and she tends to the other plants (like pulling dead leaves off ect.) while I plant the new plant. I don't mind I'm glad she is out in the sun shine and fresh air where she is happiest.... However while we were out last week working in the yard I went around the house to get the water hose unstuck so I could coil it up she picked up an outdoor table and started up the stairs with it and I came around the house and saw her. Just as I dropped the hose I heard her say" oh no "I ran the rest of the way and it was to late. I took the table away from her and let it fall to the bottom, (wanting to fuss at her & tell her why didn't she wait for me, but didn't cause it is like talking to a brick wall. She thinks she should be able to still do everything she has always done. My husband says thats the german in her coming out. (She is a tuff cookie) anyways I just held her for a few min. then we went inside grabed my car keys and went to see the doctor. She is alright but hurt her lower lumbar and the pharmacy told me to be careful with the pain killers cause she could fall, which I knew because she fell 2 years ago and broke a rib stumbled over the water hose (& they told me then about the pain killers), thats why I alway make sure it is coiled up now. The pain medication makes her stool hard and plus she can't really push because of her back hurting she has not gone for 3 days . normal for her is every morning after breakfast. It has been a week today since hurting her back. I don't really want to take her off the pain medication cause she is still hurting so much but now she does not want to eat anything cause she needs to go to the bathroom I guess or maybe the pain meds make her not hungry. I hate to see her like this Does anyone know how I could help her? the 1st day she hurt it I gave her only 1/2 a pain pill (hydrocod/apap 500) it was not enough so day 2 I gave her the whole thing and have been giving it to her that way I don't leave her alone cause I don't want her to hurt herself worse. The doctor also gave her (naproxen 500) This causes nausea so I give it to her after she eats but after days of it she has nausea regardless all day I'm thinking thats why she does not want to eat now cause she was eatting fine till yesterday. I desided last night I would not give her the (naproxen 500) pill and maybe she would eat this morning but she still has nausea, it is probly still in her system? She does not take any other meds. normally. So I was thinking maybe she could take some ibuprofan in place of the naproxen500 ? I have a call in at the doctors office now about this but they have not called back and sometimes takes 2 days for them to call back, thats what it is like out here in the middle of no where. PLEASE anyone that knows anything about back injury could you please help. Would it be best for her to stay laying down flat? or should I let here set out in the living room and alternate back and forth from the bed to setting? On day 1&2 I alternated ,she didn't seem any better on the 3rd day so I switched for 2 days to the bed and she seemed better today(with her back). I'm trying very hard to make sure she is getting enough water I know that is really important for her stool and I gave her 2 stool softeners last night and this morning too and those wont work if you don't drink plunty of water. I love her so much I know I will lose her sooner or later . She is the only family I have left. THANK YOU in advance for any and all advice sincerely Renee