Ok. So I had sex about a month and a half ago and afterwards everything was fine. But 2 weeks later I started spotting which was very similar to implantation bleeding. Then 2 weeks later I got my period and I was relieved although it only lasted 2 days. Then I had sex again and a couple of days later I started getting itchy down there and it started to slightly burn when I went pee. Then I got my next period but it came maybe 1 week early and it's lasting longer than ususal  but it's only been one more day so far and before I got it, I was spotting again, maybe a couple of days before I got it. My symptoms are similar to a uti but I don't have to urinate frequently although it feels like a uti when I do go and only a little bit comes out. Could I have an std? Or maybe my pH is just unbalanced from me having intercourse? I don't know what's wrong with me. Help please. 

Do you have multiple partners, because that is what it sounds like ? Would help if you answered.

No. I've been with my boyfriend for a year now.

You may have had the very common mid-month spotting, not implantation, but we can't possibly know (nor can you, unless you do a HPT test).
Same with STDs, UTIs, and non STD infections. There's just too many, all need different treatments, you can't often know which one or ones you are dealing with, and need to find a walk in clinic. Better yet a regular GYN, if you are sexually active.

Women who frequently get yeast infections do treat themselves, and treatments are available OTC. Itching and a cottage cheesey discharge are the usual symptoms. But when this is all new to you, you should get tested.

Your partner can get it too, without symptoms, and pass it back to you after you treat yours. So he needs to be tested too.

Do not speculate, get tested by your doctor, or OB/GYN.

Or partner could have had multiple partners, even within a year of going out with him. How well do you know him? You both should go and be tested for any kind of STDs.

There are so many STD and other infections, that without testing, it would just be guess. And many have the same signs. You really need to go and get tested

There are no doctors on this site, or any other. No doctor would risk his/her license by diagnosing online. If you want to know what's going on, see your doctor. You really won't find answers online, only guesses, which really won't help you at all.

Good luck.