Now we have proper treatment for all those cold virus or bacterial infectious diseases but what did people in the stone age or medieval era do?

We still don't have: A "cure" for the "common cold". Be aware that people in both those time frames had a much shorter life span. So, i suspect that many succumbed to infections that can now be treated. Medieval times began in 476. At that time asian's had traditional chinese medicine ; acupuncture which are still in use today. During medievil times herbs were used medicinally (as they still are in europe).