Should I be worried (bite attack)?

Mosquitoes are more active in the evening hours but it isn't unheard of for them to bite mid day. What is your concern that you've been bitten by something with more serious implications than a mosquito? If it were an issue I'd think it would have already presented itself. Unless you are allergic I doubt it's anything serious.

How is your body reacting to these bites? If you start to get more than the usual swelling and redness you might want to go in and get an antihistamine shot. Too many bites of anything can give you a major reaction.

If there's a lot of itching and but just minor redness and swelling, take a Benedryl tablet, or the generic version, and it will probably help control the reaction.

As long as you're not having trouble breathing, or your body has not reacted by getting a rash or hives over the majority of your skin, you'll probably be okay.

Ask around at your neighbor's and see if they've noticed this kind of insect. Flies come in different varieties and can bite and leave welts, and also spiders. But you should do some research in your locality. Maybe a store clerk if you're not in touch with neighbors.

make an appointment with your doctor, we can't see your bites, the doctor can give you a way better and actually correct answer.