Notising arthritis creeping into by back had me recall this post that I meant to reply to and forgot. I hope you have found that this is unlikely arthritis. My and my extended family's experience is that the discomfort is all joint related so achy thighs would not be and as for the hips it is unlikely as we would not call the pain dull it is more sharp even if a low level. Even if it is arthritis, 1 in 4 US adults will get it, it can be mild. I have osteoarthritis and on bad days I ride a recumbent trike which I very much enjoy.