Suggest Treatment For Large Bruise On Inner Calf

I have a large bruise on my inner calf. I was bitten by an unknown insect while in the woods and had immediate swelling and large lump with slight bruising after the bite. The next day and now 3 days later I have a round grapefruit size dark bruise with a small white lump in the middle. Any need for concern. Put hydrocortisone on bite immediately.

Thanks!