That could be a picture of me.
Some people attract mosquitoes due to the amount of carbon dioxide they emit, along with other chemicals. Infants and children may even have "skeeter syndrome," in which each bite gives rise to a giant, itching hive which enlarges for 8 to 12 hours and goes away in 3 to 10 days. They outgrow it. [Unless they are you or me.]
My favorite anti-itch medication is Benedryl. You can take it orally, or you can apply a gel or liquid, but you can't use both. I use the gel, mostly.
Applying heat to the bite helps. I run a washcloth under hot water, wring it out, and apply it, and the itch lessens. Tip: scratch all around the bite if you can't resist scratching. The relief is about the same, and you won't rip it open.
The welt is an allergic reaction. Oral Benedryl minimizes it (but doesn't stop the itch as well).
Repellents containing DEET are good. So is picardin. For greater protection, use a repellent with permethrin on clothing. But then you smell of mosquito repellent, and the good ones destroy nail polish.