The mosquitoes biting this year are worse than last year aren't they?

It sounds like you may be having some sort of allergic reaction. Allergies can develop even in adults, even after years of exposure. I have allergic reactions with ant and mosquito bites that can get to be the size of quarters and larger, especially at first. I live in Texas where it has been raining almost constantly all summer, but I haven't noticed a change in severity of my reactions to bites.

As for the bruising, I'm not really sure how to explain this. For decent relief for the itching, I'd suggest hydrocortizone cream, or even Neosporin works in a pinch.

Probably a bacterial infection from scratching the bite. Go around your house and make sure there is no stagnant water. The average mosquito is born within 100 yards of where it dies. Deet is the best to keep mosquitos at bay. Some people might be allergic to deet, if so use picadarin.

It maybe because of a prescription pill or some medicine you may be taking this year .A few years ago I had large swelling after a stout stung me (deer fly) but it was caused by a herbal remedy pill I was on.It stopped as soon as I realized this and discontinued it.