This morning I went to the osteopath at the sport center for my hip (unlike the swimming pool, it's unfortunately not free). She moved my legs around and pressed a lot on the back of my right hip, which was rather painful. I'm now writing this entry with a bag of frozen peas in my pants :-/
I hope this will be useful, otherwise there's not much else I can do... At least it was not general recommendations such as to drink water, eat healthy and stretch after exercising.

Ultra manipulations.