Spotting two weeks after period, one month after sex. Am I pregnant?

I had unprotected sex May 13 (it is currently June 16) and then two weeks later I got my period as I was supposed to (I am on the pill). However, today and yesterday (two weeks after having my period) I have been experiencing spotting. I have also been exhausted and experiencing abdominal cramps and a mixture of constipation and diarrhea depending on the day. I have taken three dollar-store pregnancy tests (these are all I can afford) and two were negative and one was invalid. I have never experienced spotting before, however, and I am unbelievably concerned that I am pregnant. What are the chances of me being pregnant? Could this be implantation bleeding a month after sex (and two weeks after a period?) And if I am not, what else could explain all of my symptoms, which align with pregnancy symptoms... thank you very much.

If you're on the the pill, have had your period, and have had two negative pregnancy tests, then I don't see how you can be pregnant.

Other things that can cause spotting between periods, are

ovulation

just being on the pill, especially if you've only been taking it a few months,or if you've changed the type of pill

chlamydia

fibroids

cysts

It's probably nothing serious, but given your symptoms, you should probably see a doctor.  I honestly don't think you're pregnant though.

Good luck, and let us know what the doctors say.

Thank you so much!!! I missed a pill Tuesday (took it with my Wednesday pill) so maybe that's a factor... I have been on the pill for five years (this specific brand for around 1 or 2) and I have never had this happen, so I'm hoping it's one of the other things such as a fibroid. I can at least tell my mom about that one because I could never tell her if I'm pregnant and I would have to pay for all the costs by myself (and I just graduated college and have not yet found a job...). I have an appointment set for Monday, so hopefully my anxiety doesn't get too bad over the weekend because it's going to be a hell of a waiting game until then... I'll keep you updated on what the doctors say. Again, thank you. You are the only person who has replied and I have posted this question so many places because I have nobody in my life who I can ask. Thank you

Missing a pill then taking two in a day could definitely have caused the spotting, cramping, and fatigue, and potentially the diarrhea/constipation (google "missed pill bleeding" or "missed pill side effects&quot.

If you google "missed pill rules", there are various instructions about what to do, depending on what pill it is and when you missed it, though you should read the instructions that came with your particular pill.  

This is what this website says (referencing UK brand names):

https://patient.info/doctor/missed-contraceptive-pills

** Note that depending on which pill you're on, and when you missed it, you may need to use condoms or abstain for a few days. **

It might be worth setting one or more alarms on your phone to remind you to take the pill.  It's best to take it at roughly the same time each day.

Good luck on Monday, but I think you'll be fine.