The other thing that might help and some people (including us ) have found that a couple of paracetamol before bedtime helps settle someone and combined with lighter bedding this might at least reduce the problem, including the pain.
Regarding the pain I would advise you to go back to your GP and continue to speak to him this - I am so sorry, you are really having a hard time
Have you had a carers assessment to get some hours to give you a bit of break - it is worth phoning social services and asking for a carers assessment.
Also if you are not getting Attendance Allowance then you should be - at the higher rate given the night care you are doing. This is non means tested and it is a really useful amount of money to help you with all the extras like the higher electricity bill and maybe some caring hours - I think it is currently at about £80 a week. Give Age UK a ring on their freephone number 0800 169 2081 and tell them you would like some help with filling in the form - they have trained volunteers and the forms are very tricky. Tell them about your situation and they may have some other ideas too local to you.
The Dementia helpline is a useful number to have
Alzheimer's Society National Dementia Helpline 0300 222 1122 can provide information, support, guidance and signposting to other appropriate organisations and may also be useful
Keep posting, lots of support on here