Hello and welcome to HCM,
An insect bite/ sting has to be treated with antihistaminic drugs.
The
redness, soreness and pain associated with insect bite is caused by release of
histamine and other mediators of inflammation.
You need to take antihistaminic drugs.
Painkillers can be used for associated pain.
Topical antiseptic cream can be used to prevent the infection.
The
lymph node enlargement that you are experiencing is likely to be due to the inflammation caused by the sting.
However, you need to consult your doctor for clinical assessment of the lesion.
Infection has to be ruled out.
There is high suspicion of infection due to presence of swollen red arm.
Thanks and take care
Dr Shailja P Wahal