Hi I Was Swimming This Morning And Hit My Head

Hi I was swimming this morning and hit my head in the pool (backstroke). I recently finished chemotherapy and last week they discovered an intra-muscular blood clot in my calf. They started me on heparin injections last Thursday. Do I need to worry because of the blood thinner?
I feel ok, the spot on my head where I hit is mildly sore, I am told by others it is a little red, and I can feel that there is a little bit of a bump there. Should I still do my heparin shot today at 2 pm, or skip it today?
Diane