I have one bite on my arm it was like a welt and itched then went to hard and sore could it be bed bugs?

May be infected.: If only one bite,and nobody else in your house has it, doubt bed bugs. But a bite that gets hard and sore may be infected and you might have an abscess. Don't try to pop it. Apply hot compresses for 30 minutes four times a day and get it checked if it gets bigger, more painful, or you have fever right away. If it is large, (bigger than a marble, get seen. Sometimes antibiotics can help.

Bed bug bits: may have no sx's/signs except for 2 small skin puncture points. A reaction may show from 1 hr to several days later. It can cause itchy, pink, swollen, lesions w clear center. If hypersensitive blisters may occur. Telltale sign is linear track of lesions from sequential feedings – doesn't always occur. Bites are in areas exposed while sleeping-arms, shoulders, neck & legs.