Tampons throwing off pH levels? Help!

Wondering if anyone else has this problem, every single time I get my period I use tampons, now I have a heavier flow so I keep a tampon in all day and change it every 3ish hours.. but without fail a couple days in my period I get this strong sour smell, I can litterly smell myself while I change my tampon it is disgusting. Anyway to solve this problem? Is this normal? Maybe I should try out a diva cup or something? I've never tried one due to being scared it'll overflow with my heavy periods.