I thought I had low-T as well and I'm 27. I went to see my GP and even though he told me I was "way too young" to have low-T he ran the test any way. Test came back normal for T-levels and he said I had a vitamin D deficiency, which would explain my tiredness, depressed mood, etc.
As for why you don't get sexually excited, perhaps you're engaging the wrong stimuli? You're a young guy, so you have a lifetime to find out what gets your engine going, but my non-medical opinion is if you're not sexually aroused by what you're doing (or WHO you're doing) then find something new that excites you.
Have your doctor check your testosterone level it's a simple blood test and as I said some meds. can affect it. If they do ask your doctor if he can change your meds.
Hi yes but the problem has been before taking them
Are you on any medication for anxiety or depression? some meds. can cause the problem! If you're on any meds. talk to your doctor.