My Son Has A Small Lump On His Upper Thigh.

My son has a small lump on his upper thigh. At first, I figured it was a lymph node. It doesn't hurt when touched and has increased to about the size of a medium vitamin capsule... my mom said about the size of her fish oil. We are going to the doctor tomorrow, but I didn't know if I should brace myself for anything too serious. He has had an abscess in his throat before where part of the lymph node broke off and caused th e abcess... they drained it and put him on blood thinners for the large blood clot that it had caused in his jugular vein. He is almost 3.