I have been bitten or stung on my arm and a lot of the area surrounding has swollen quite a lot and my arm does feel weaker is this normal?

WatchItClosely. This is a case of needing to see it in person or at lest a photo. An insect venom reaction & an infection can look quite the same.If you were bitten within the last 24 hours then the chances of an infection is less. They usually develop over 2-3 days.When in doubt, though,it needs to be examined.So see if it levels-off over the next several hours.If not & it hurts a lot & you get a fever,see a doc.