Do I have Bed Bugs? I'm not quite sure.?

two days ago i woke up at about 4 in the morning to find my leg and my arm itching. When i got up i noticed small mosquito like welts on my arm and leg, not a lot of them but about 8 or 9 total. I thought maybe a spider got caught in my sheets and ignored it. Today when i woke up i had a few more bites on my right leg, but no new ones on my left leg or my right arm. I throughly checked my bed, changed my sheets and used a flashlight under my bed to look for any signs of bedbugs. I looked in between cracks of my bed and only found dust. Am i just having an allergic reaction to something? or do i most likely have bed bugs? if i have bed bugs, what should i do?