Mr Powell said his local minor injuries unit “100%” saved his life, along with his friend who answered his call to take him there.
“Otherwise, I wouldn’t have got there in the car I don’t think, because I was going in and out of consciousness,” he said.
“If there’s no MIU (minor injuries unit), I wouldn’t be here”.
The MIU in Brecon is currently open 24 hours, seven days a week, but from September it will temporarily reduce its hours to 8am to 8pm.
There have been calls locally for Powys health board’s proposals to be scrapped.
Kate Wright, executive medical director at the health board, said community hospitals in Powys do not provide acute care and that MIUs are often having to close in the evening “at short notice” due to trained staffing availability.
The board is encouraging people to take part in its consultation to have their say on the proposed changes.
The advice from the NHS to treat insect bites or stings is to put an ice pack wrapped in a wet cloth on it for at least 20 minutes, if swollen.
People are also advised to keep the area raised if possible, take painkillers if painful and use antihistamines and a hydrocortisone cream to reduce itching.
But the NHS says people should neither scratch the bite or sting nor use home remedies such as bicarbonate of soda.