Last two times I was bitten by insect (mosquito), the wound would not go away for few months. The first one kind of healed, but it left small bump on my arm. The most recent one still shows on my arm, it doesn't hurt, doesn't itch. I worry why all of a sudden they do not go away in few days as they used to. I also became allergic to bees' bites.

Anybody has idea why the bites do not go away/

Thanks in advance