Anxiety or actual physical condition/pain

I have posted several physical and possible mental issues that have recently arisen in my life. I am not sure if it is all anxiety, suffered a panic attack, or if my feelings/sensations are genuine and not in my head. Anyway, now I'm dealing with a tailbone issue that appeared out of the blue.

I cheated on my girlfriend four weeks ago. I became so fearful that I was infected with HIV that I've been tested for all STDs three times. (No, I did mot wear a condom). Tests show so far that Im completely negative after 28 days. But the fear of HIV started consuming my life that all I do is go online and look at my symptoms (muscle spasms twitches and looking as to why I became very ill after 36 hours of having sex with this other girl). 

So my new problem started after having sex with my girlfriend, who I hadn't seen in three weeks. I have never told her that I cheated on her.

My tailbone began to ache with a warm radiating sensation. I have never experienced this pain or discomfort before. I started wondering if I pulled a muscle or if it's possible at all. 

I went online searching for answers. It appears I'm suffering from coccydynia or coccygodynia (pain in the tailbone). 

Besides physical injury, which I believe did not happen, there are a few explanations for this pain. 

I remedy the problem by laying on my side when sleeping. But if I'm awake and the pain appears, my whole body aches. It does not happen all the time and it appears triggered if I'm sitting for a long period of time or am stressed. Pain comes and goes on it's own. 

On a side note, besides possibly exposing myself to HIV and cheating on my girlfriend, the last 30 days have been the most stressful in my life. 

So my question is this a condition? Am I infected? I was tested three times and as recently as this past Monday and again came back free of all STDs. Is it a disease? Could I have damaged the tailbone during sex (no, sex acts were not nor have ever been performed in or on my buttocks). Or is it stress? Maybe extreme anxiety or am I suffering panic attacks?

Please, I need some answers or at least some examples of how to cope with this issue. Right now I'm so scared and want to completely withdraw from the world around me. I become so obsessed with all my conditions that I'm basically worthless at work and am  consumed in deep thought.

Thank you. 

[M4Y0U]

Have you investigated on your posture for your tailbone? Do you spend a lot of time sit? If so maybe you could use something comfortable to sit on.

It is often reported that people that cheated on their girlfriend will develop anxiety symptoms (muscle spasms and twitches like you said), guilt and will come to the point that they fear HIV. One thing you must know is that for 1000 HIV tests at least three will come back will false negative result mostly due to the ''window period''. Which means you can be infected even with a negative ELISA/Western Blot test. Nowadays we can do PCR, they are much more accurate. I can't tell you that you don't have HIV because I have no idea but I can suggest you a PCR test. If all you other STD tests came back negative then I doubt you have a STD other than HIV.

Now back to the tailbone. I did experience something similar a while ago when I was under great stress. My posture was not ideal too. Is it stress or a postural problem? You will be the one able to answer that. I don't deny that an X-Ray should be done to rule out any possible mass or luxation. I do really think your problem is idiopathic coccydynia and it is probably related to posture and/or stress but better be safe than sorry so I encourage you to go for the tests.

If all your tests come back negative then I do really think it should provide a good relief for your anxiety. Right now you fear the unknown but with today's advance in medicine we are able to diagnose efficiently most diseases. Knowing there is nothing wrong will be a relief.

M4