what kind of wallet?
I think its called Bitcoin Core or bitcoin-qt? does that make any sense to you?
can you try to do a scan with malwarebyte anti malware, and hitmanpro?
see if there is something malevolous
also i suggest you to use zemana free anti-logger, it hide your key-stroke
i did perform a malware scan, and oddly found malware dating back to backup files i saved back in 2005. I dont think bitcoin was even around back then so im not sure if that would have caused it. I used malware-byte. I think as someone suggested, might be best to format and reinstall the OS along with setting up cold storage.
Anti viruses are not always correct and shouldnt be your only defense against viruses. Antivirus merely checks the signature of the files on your computer with their servers to make sure you dont have any files that matches those known viruses that has already been detected. There are lots of virus that has not yet been detected. Your best protection would to be not downloading suspicious files or going to suspicious websites.