Here you go! Hopefully that'll help you to work out whether you've been bitten by a sand-flea or not.
Is A Sand-Flea Bite Dangerous? Not particularly, no. However, sand-fleas can carry dangerous viruses, such as the Chandipura virus (similar to Rabies).
Despite being painful and itchy, sand-flea bites are usually relatively harmless and will start to fade after a few days.
How Can I Prevent Sand-Flea Bites? There are actually quite a lot of things that sand-fleas don't like. I can't guarantee that any of the following things will protect you completely, but they should make the sand-fleas look elsewhere for their dinner!
Citrus oil or peel
If you rub any of those things over your skin before you go to bed, you should be a little more protected from sand-fleas than usual. I wouldn't recommend using vinegar, though - it doesn't smell very nice!