If the blister was caused by his shoes, place a band aid over the area and wear loose fitting shoes to allow it to heal.
Allow lots of air room, let him go barefoot as much as possible. If it hasn't popped yet you could sterilize a sewing needle and pop it. Place a band aid over it right away so it doesn't become infected.
If it has popped already, make sure to take him to the doctor if you see yellow pus coming out.
If he develops blisters in his mouth and on his hands as well, you'll need to take him to a doctor.
Does he have diabetes?
People with diabetes heal much slower.
Make sure you don't rip the skin off of the blister, as this will allow for infection.
I cannot confirm a diagnosis without examination, but it can be foot blisters.
When a foot is hot and sweaty, the sock sticks to the foot. The sock and foot then rub against each other and the inside of the shoe causing blisters to appear.
Your son should wear shoes that fit properly and keep feet as dry as possible. Wearing wet shoes, boots and socks will increase your chance of developing blisters. So change socks regularly.
And use foot powder to help keep your feet dry. If the blisters still persist then get it evaluated from a dermatologist/podiatrist.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
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