Lower back pain
 

When I pedal for long periods without a stop, my lower back starts to hurt and then I know my right groin is going to start aching and it will keep on aching for some days. This pain doesn't make me feel like stop pedalling but it is rather anoying.
I made an x-ray sometime ago, there was a text with the x-ray which said I had acetabular sclerosis although the bone showed no defect it suggested problems of the acetabular labrum. After this I went to an orthopedics specialist he didn't care about the text and he took a look at the x-ray and said there was nothing wrong after some movements with my leg and some touching (I don't know how to swy it in english) he said I had bursitis, this would always hurt but no need in any special treatment.
Who is right the doctor who made the x-ray or the other?

This is really bugging me is there anyone out there who can give me an opinion?

Thank you!!

As far as the medical stuff goes, a second opinion from another doctor might be in order.

In any case, it also sounds like you would benefit from having a bike fitting to make sure you are in the most ergonomically correct position when you ride.

Never heard of a bike fitting service in Portugal unfortunately.

But I exchanged the stem in my bike for a longer more flat one and since then I've had trouble. Never thought about that as a cause of trouble. How muche should I shorten it to make the change effective.