Pain in one spot during sex

I am desperate for some type of response as I am a huge hypochondriac and am nervous there could be something majorly wrong.

About a week ago it hurt during sex for the first time. It is strange because I have absolutely no other symptoms and it feels as though it hurts in one specific spot inside. It is not pain all over. It hurts for awhile after having sex as well. It is not an intense pain, it is more mild and dull.

I am in a monogomous relationship, so I doubt it is an STD. The only thing that I can think of being a trigger to this is I bought scented tampons by accident and was using them. My period had just ended.

I have some spotting after sex, but I believe it is contributed to being on the Depo shot which I just started at the beginning of the month. I was on it before and had the same issues.

If anyone has any idea what could be the problem please let me know. I plan on calling the doctor on Monday, but would like some insight beforehand.

Oh, and we did try using a lubricant and it only helped slightly.

Thanks so much!