I agree with @jordym84 that possibly it isn’t mosquitos.
It is true that we can develop allergies over time. Our bodies can decide something is bad and start sending out more fighter reactions that cause inflammation. Unfortuneately our bodies get better and better at recognizing and reacting to the antagonist, which means the body actually gets better at sending out fighter cells.
I would just put topical benadryl spray, calamine lotion, or cortizone cream on them. I never take a pill. But, I hate taking pills.
If the area of redness is growing that can be cellulitis. If it is getting bigger and bigger and it is very uncomfortable, not growing round, but towards your heart, that is a clue, or if there are red streaks coming from the area. If you aren’t sure you can draw around the edge of the red area with a ball point pen. Cellulitis can grow a centemeter every 12 hours or faster. It must be treated ASAP. But, if it is multiple bites reacting, then it is unlikely it is cellulitis or infected in any way.
And, buy some repellent, and I am sure you know this, dress with long sleeves and slacks from dusk throughout the dark hours. If yu are walking through the woods and grassy areas consider wearing closed shoes and tall socks to protect your lower legs. I know that sucks in the summer. It could be chiggers or some other bug.