You mentioned several symptoms common to low thyroid:
1. Low energy
2. Gaining weight
3. Feeling lousy
4. Can cause other sickness
5. Feeling cold especially the hands and feet - classic symptom!
Get a thyroid test. It may be as simple as low thyroid. If that is what it is, you will take meds and in a few weeks will begin to feel great again. Concerning sex, be very careful these days. Make sure the one you are having sex with is healthy and monogamous. It isn't worth getting a disease for a little pleasure. Use protection, which you said you did, that is good, but don't engage in oral anything until you know for sure the other person is healthy and is not sleeping around.
Thanks for your prompt reply, my doctor had test the thyroid and he said it is normal , I am really feel helpless.
I am wondering about adrenal fatigue. It is similiar in symptoms to hypothyroidism. Weight gain, depression, brain fog, sometimes lightheaded when getting up from laying down, low libido, tiredness, lack of energy in the afternoons. Does this sound like you? If it is adrenals, you can take magnesium, Omega-3 fish oil, Super B-complex, these will help. You can also asked to be checked out for your adrenals by your doctor which will probably be adrenal insufficiency testing. Hold on, there is hope. Eventually you will find out what you have and that is half the battle right there. On to something else. Do you have muscle pain or stiff joints too? Any rashes and if so where? Is the weight gain more bloating or it is actual weight?