Ive got what seems to be a bite on my foot, to which i left for a few days & has now swollen i have also been experiencing groin muscle pain on the same leg which im assuming from an artery , as it seems swollen

Needs evaluation : This sounds of concern for an infection under the skin with bacteria that entered through the bite, & the groin pain/swelling could be lymph nodes fighting the infection. This can be very serious if not treated with antibiotics- you need an in person or video provider visit right away. If you take your temperature at home that information helps greatly as well - fever is more serious

Bite: Your should be seen. I do not know where you have been and it would be difficult to determine this online. Spider or snake would be most likely. Either way if you have evidence for that type of swelling you should be seen.