Stiffness in knees hips legs

Hi all I've had six cycles of chemo (carboplatin) which I coped well with. Just awaiting results of CT scan to see what happens next. Feeling the old scan anxiety kicking in as we all tend to. Trying to take short walks as being in fresh air helps.

However the last week or so I've noticed stiffness sometimes in one knee other times in the hip or leg. At times struggling to get socks on or off. On Wednesday after sitting for two hours I was limping round the shops. I used to do several gym classes and aqua aerobics before all this **** plus Pilates so was pretty active. I'm wondering if lack of exercise has contributed to the problem, if chemo played a part ?? Is it old age almost 61. Did suffer a few years ago with my right hip giving way but it just got better. 

I've tried paracetamol or ibuprofen not sure which is best but only occasionally as it's stiff not painful. Heat via trusty hot water bottle eases it off. Trying to do some basic pilates stretches. I'm conscious I'm lying around more watching telly not really moving. Some days it's no problem then today I've struggled up the stairs. 

Any advice or anyone affected in the same way?

Many thanks