A Cluster of Bumps (Hives)
If you have a cluster of red and swollen bumps on your skin, it could mean that you have been bitten by more than one bedbug. You can tell that you’ve been the host for multiple bedbugs when you wake up to see lines or clusters of inflamed spots, usually on your face, neck, back, or arms.
These clusters can have uneven or varying shapes and may trigger a burning sensation that makes you itch.
If you give in to the feeling of scratching these spots, it can worsen and cause bleeding or an infection.
In rare instances, a bedbug bite may cause serious symptoms that include: shortness of breath, fever, blisters, inflamed tongue, nausea, vomiting, difficulty swallowing, and abnormal heartbeats.
Reference：
[1] https://www.mayoclinic.org/diseases-conditions/bedbugs/symptoms-causes/syc-20370001#:~:text=Bedbugs%20are%20reddish%20brown%2C%20oval,to%20feed%20on%20their%20blood.
[2] https://pointepest.com/bed-bug-faqs/scent-keeps-bed-bugs-away/#:~:text=Many%20bugs%20are%20repelled%20by,tea%20tree%20oil%2C%20and%20lavender.&text=One%20known%20scent%20that%20repels,nymphs%2C%20or%20baby%20bed%20bugs.
[3] https://www.webmd.com/skin-problems-and-treatments/guide/bedbugs-infestation
[4] https://www.healthline.com/health/bed-bug-bites