Scar tissue problems- can it get infected? Possible debris in healed wound?

Patient: About 3 months ago I fell in a lake that I later found out was closed to swimming that day due to high unspecified bacteria levels. Cut across ankle about with two 1/2 inch puncture wounds going down toward foot (no exit, only created a pocket under a few layers of skin). stopped the gushing blood easily but wound leaked blood for about 4 days(no white blood cell weeping for almost a week) yet still healed very well, except for some swelling right below the puncture wounds due to lack of drainage. Swelling went down with foot elevation. Never signs of infection, but was not professionally dibrided. 2 days ago I cut a small white cyst- just tissue, no infection- out of the end of the scar that is near the top of my foot. Now it is swelling again in the same spot as the fluid accumulation (under my outer ankle bone), which feels like there is something other than what belongs there under the skin, as well as the top of my foot. No signs of infection. What would you suggest I have my doctor check out? Organisms from the lake still in old wound? Inside of wound still healing? Why could the swelling start again from out of nowhere?

Symptoms: Swelling, cut out cyst earlier, puncture wound