1-is there a treatment for pityriasis rosae gibert? 2- if I have pityriasis rosae can i: a) swim b) run/play tennis

Yes, yes, yes. Treatment for pityriasis rosea is generally aimed at the symptom of itching. Topical steroids and oral ant-itch meds are usually enough. Sometimes systemic steroids, like prednisone, or ultraviolet light treatments are needed if itching doesn't resolve. Okay to swim, okay to play tennis. Sweating could make itching worse, if it's already a problem.