Welt-like Hives?

hello. my whole body has been itching everyday since 3-4 days ago. it doesn't itch the whole day but i guess when my day becomes calm, it starts to kick in. i don't kno whether to consider this a allergic reaction or something more? i haven't been to the doctor yet but will go after i could get some ideas...

3 days ago. it was sunny, 13-15C (59oF) i am a university student first year midterms are now (stress induced?i did get a bit sweaty that day walking around (overweight) and during the day my body just became more itchier and itchier. started at the head first then worked it's way down. i took a claritin and didn't work. only thing i consumed that day that i wouldn't consume any other day was caffeine (tim hortons steeped tea)

next day it got colder to aorund 2-5 oC. wet and cloudy. also had a tea that day.

last day (yesterday), it was below freezing some points of the day. no caffeine today and i wore the same jacket-hoodie i wore the past few days but took showers. yet today it seems like the itchiness was most severe at night time and out of the past few days.

can it be temperature-induced? sweat induced? caffeine induced? anything? please i need an answer,