Darky:
The truth is that if you have one autoimmune disorder, your chances of acquiring another one (or two) is greater. That does not mean that it will happen; many people only have ITP. However, there are quite a few people here that do have more than one. MS is one of over 100 autoimmune disorders, but it is not singly associated with ITP. I was diagnosed with Lupus 8 years after I was diagnosed with ITP. The most common autoimmune disorders we see here seem to be Lupus, Graves Disease, Hashimoto's, Autoimmune Hemolytic Anemia, Antiphospholipid Syndrome, Evans Syndrome, and MS.
Your symptoms do not seem to be very specific to any disorder and could be due to many things. Fatigue and insomnia are common and could be due to something as simple as a Vitamin deficiency. The problems with your uh, sexual dysfunction could be age related possibly? I don't know how old you are. I'm sure there are other reasons both physically and emotionally, but you'd need to speak to your GP about that. Pain in fingers can also be related to age or steroid use...arthritis, etc. They could all be separate things and not necessarily linked to one specific disorder. Maybe start with having Vitamin levels checked. It's simple and easy to fix. Then give it some time. If things get worse, you'd need to pursue it. Doctors tend to blow people off when they come in with diffuse symptoms that do not appear to be readily visible like swelling, rashes, weakness, apparent stiffness, weight loss, etc....so if things progress you'd need to be more insistent. As it stands right now, you do not have a diagnosis so I'd stop worrying unless things get worse and you do get one.
PS - Fatigue is a symptom of Vitamin D deficiency. It can take a long time to recover from that since it can weaken muscles.