I need advice!

So I've been talking to this guy, he's 25 I'm 19, for about a month and a half and have been sexually active. Recently I've started noticing this bad vaginal smell and I'm concerned it could be an STD. I'm afraid to go get tested because it would kill me to tell this guy I gave him an STD. I feel as if in my last relationship he was unfaithful in the end and caught something and gave it to me and it's now acting up because I'm becoming sexually active again. Any advice please!