Yes, but they work best if taken immediately after the sting, before the swelling sets in. Once the capillaries are dilated and leaking from the histamine effect, all the antihistamines can do is slow it down from getting much worse. You need a decent strength antihistamine too. In Australia, I would suggest Phenergan. In the US, Benadryl is the best choice. I discussed it here:
Ibuprofen and naproxen will reduce pain, but may actually may the swelling worse. If you want to know why, I put everyone to sleep with an explanation here:
If the swelling is really bad, you might want to see whether your doctor would be willing to give you a short course of steroids. That will block both of the biochemical pathways which cause swelling and pain from the sting.
You could also try the sprain approach to help the swelling reduce more quickly. Elevate the hand as much as possible when you are not using it. If you have a medical ice pack, put that on 3 times a day for 20 mins. If you don’t have an ice pack, put some ice into a large ziplock bag, wrap the bag in a towel and hold that over the swollen area (the towel helps prevent ice burns).
I don’t think so. From the medical literature that I have read, in non-allergic individuals the thing that most affects the severity of the reaction most is how long the stinger was left in place. The faster it is removed, the less the reaction. They also have studied whether squeezing the venom sac matters. The answer is that it is more important to get the stinger out fast by any means available, than to worry about squeezing. Scraping it out with a fingernail is just fine, failing that, a credit card works well.
Hope you feel better soon! 