very swollen insect bite

i noticed an insect bites on my knee around friday the 4th june, and of course as usual it was itchy.
so as usual, i itched it every so often but nothing excessive. it wasn't swollen nor was it red...
but last night (9th june) it started to get really hot and extra itchy than usual...
now today, the 10th june, it's been very difficult not to itch it.

the appearance of this bite is raised, my knee is swollen, maybe 1cm larger than usual,
the bite itself is red, then there is a white ring around the bite, then continues to colour red
it seems to be a rash, 1-2 inches around the bite mark, and there are small bumps surrounding it.
i have another slightly smaller bite below my knee, which is alot less red and barely swollen, yet still as worrying.
and lastly i have ANOTHER bite (insects love my skin!) on my elbow. this one is not raised, now red or that itchy,
however i only recently gained this, around the 7th/8th.

i've taken an antihistamine tablet, three hours or so ago, but it hasn't seemed to work just yet.
i'm worried! my boyfriend said i may have an allergic reaction, and could go into shock
if the swelling and redness is still here by tomorrow night, i'll be sure to see a doctor.

what is there that coule be possibly wrong with it? an infection or an allergic reaction?
help me!