I have a similar problem, too. I'm not doing so great with sticking myself these days.
On Fri, I injected into my thigh. No problems. Wiped the bottle, used a new syringe to draw, drenched my thigh in alcohol, used new a 23g 1" tip and pretty much buried it. Aspirated. Injected a tiny amt and waited 30 sec. Injected the rest of it.
Blood came out when I pulled out. Guess I nicked a vessel. No big deal.
Saturday AM, I was fine. I did legs at 1pm, I stretched out first and was feeling limber and good. Saturday night (same day) I went in to sit in the sauna and I realized that my leg was a little swollen by the kneecap, not where I injected.
It's visually puffy and I can't bend it much. Feels like it's full of fluid.
I'm going to monitor it. If it gets any worse, I'm going straight to a doc. I think it would be good to have a bottle of doxycycline on hand, just in case it happens in the future.
It's one of those "what the hell" type of things. Anyone have any idea what happened?