Poorly cat - stomach ache or back ache? Constipated?

Last Thursday our nearly 8 year old Sparky wasn't well at all. She wouldn't settle on Wednesday night and kept scratching at our bedroom door. She woke my hubby up at 4am doing this. This isn't like her at all. She went for a number 2 and then kept going back to the litter tray and straining to go. She hadn't eaten much for the last two days. Eventually she managed to poop a bit more but got it stuck and tried walking round the flat licking it off. My hubby had to pull it off. We took her to the vets and she was checked over but they said she was ok. She was given an anti-inflammatory injection which she proceeded to throw up when she got home. She therefore spent the next 24 hours at the vets. They got her eating again, gave her pain killers and said they could see she was straining to go more than another cat would. We were told to give her painkillers once a day until yesterday, give her wet food only (she had previously only been on purina pro plan senior 7+ biscuits) and to watch her toileting behaviour. She went on Saturday and then again this morning. We didn't see her Saturday but this morning I watched her and I don't think her back was arched as much but I was at the wrong angle to tell and didn't want to disturb her by walking past! What she is producing seems normal. 

The vets couldn't tell if she had back pain or stomach pain. Every time they touched both she complained. They asked us to check but she seems fine with her back being touched and the one time she let us touch her stomach, she seemed fine. But she was still on the pain killers. 

This morning she started scratching at the door at 5.30am again. Not sure if this is going to be normal for her now (we've only had her 6 weeks) or if she is still ill. 

Any advice?

Sorry no one has answered you before this.  I am only now seeing your message. The only advice I would give is to add canned pumpkin to her food.  I had a cat who had this problem once and the vet told me to do that an it helped because it is high in fiber and it made his stool softer and easier to pass.  When I first got him (he was a stray wo showed up at a friend's house), I named him Piglet because he had a huge belly.  I took him t the vet for a check up and they said he was very constipated, and they kept him a couple of days and the poor guy got enemas until he was cleaned out well.  Then they told me to feed him wet food and mix in canned pumpkin (just plain pumpkin, not the pie mix that has spices in it).  He liked the pumpkin and he did not get constipated again. 

Since you have only had your cat for six weeks, you don't know her history.  It would be good if you could find out more about her from her previous owner, and if she came through a rescue, then get whatever information you can get from them.  They may have the name or her previous owner and while they would not give it to you, they might be able to ask that person to call you or email you, which they will do if they care about the cat. 

As for her scratching at the door, I'm not clear whether she is IN the bedroom with you and scratching to get OUT of the bedroom because her litter box is in another room, or if she is shut OUT of the bedroom and scratching to get IN, and then leads you or your husband to the litter box where she demonstrates she is having a problem.

Let us know how this is going.