It does sound like classic Low-T symptoms but of course there could be many other things going on as well. You could lose 20 pounds and feel great again who knows. The best person to see is either a Urologist or an Endocrinologist but I would start with my General Practitioner and get some baseline labs done.
If you do need to go an HRT (Hormone Replacement Therapy) route be aware that not all doctors are created equally and you may need to shop around for one experienced in this area. Also, don't fall for the anti-aging clinic nonsense they do the same things an experienced Endocrinologist/Urologist will do but charge you 10 times the price.
No need to be nervous or embarrassed the doctor has seen and heard it all, much crazier and disgusting things than what you are experiencing believe me. When you set the appointment it's not the receptionist's business what the appointment is for she's only trying to determine how much time to allot you, so say you have various issues you'd like to discuss and also get a general checkup.
Likewise the nurse who comes into the room first before the doctor gets there. Don't be rude but tell her you'd prefer to discuss things directly with the doctor. She's only trying to save the doctor some time by writing things down in your chart in advance. If you do tell her the issues just be brief and general, she isn't qualified to make diagnoses nor is she attempting to, as I said she's just helping with the notation. Many people go overboard with the nurse with detail and then don't share the same level of detail with the doctor because they assume everything will be relayed. This is false and the opposite should be done.
Here are the labs you absolutely MUST have done if you suspect Low-T. Do not accept no for an answer as if you end up going to a Urologist or an Endocrinologist they will be ordering these labs immediately anyway. Tell the doctor you have done some research (which I encourage you to do, after all you don't know me) and insist on a full workup.
Good luck!
The Labs you need:
Complete Blood Count (CBC) -
full blood workup
Liver Enzymes AST and ALT -
liver function test
Free Testosterone -
this is the number that is truly important not Total T, it's calculated from total T though so you need that also
Total Testosterone
Estradiol -
Estrogen levels,extremely important to have tested and many doctors don't want to do it, high E in men causes the same symptoms as Low T
Prolactin
Sex Hormone Binding Globulin (SHGB) -
SHGB binds to Testosterone leaving less free T
Prostate Specific Antigen (PSA)
Leutinizing Hormone (LH) -
This and FSH are important so you can see if the problem lies with your testes or your pituitary gland, often referred to as primary or secondary hypogonadism
Follicle Stimulating Hormone (FSH)
Thyroid Stimulating Hormone (TSH) -
Thyroid test along with T4 and T3 to rule out thyroid problem
T4
T3
Some research to get you started, you can pass these along to your doctor if he gives you a hard time...especially the first one:
Carnegie, Christina. "Diagnosis of hypogonadism: Clinical assessments and laboratory tests." Reviews in Urology 6.Suppl 6 (2004): S3.
Pantalone, Kevin M., and Charles Faiman. "Male hypogonadism: More than just a low testosterone." Cleveland Clinic Journal of Medicine 79.10 (2012): 717-725.