I'd second the suggestion of going to a sports med doctor - and I would suggest doing that before jumping into PT. I had very similar presentation (pain on the upstroke of the pedal when the hip is bent 90 degrees or more as you describe) - I had low level on and off pain for 10+ years, increasing in frequency and intensity over the last year to where I really couldn't cycle anymore. Turned out to be femoral acetabular impingement (basically a big bone spur leading to a large hole in the femur and a torn labrum) and I had surgery in July. I'm on the road to recovery and the hip honestly felt better the day after surgery than the day before.

So, anyway, I hope yours is simply a muscle imbalance, but it wouldn't hurt to get get really checked and get an x-ray because if I had tried to heal my issue with PT alone, I would have done a lot more damage to the hip joint and the femur.