Any ideas

I been on the swim team for the last three months I haven't lost any of my tummy and according to the scale I gained 20 pounds and gotten new stretch marks from just gaining muscle (I know its just muscle weight) but I am 5'2 and 158 pounds and I need to lose this weight and to leg problems I can't do running because it gives me very bad hip pain because I have short heel cords in my legs and I am so disappointed in myself for not losing even a pound of fat and the season for me is over tomorrow anyone have any tips I would really love of if I could get some