Worried. STD or something else?

So symptoms I am having is 1. Not able to have as strong ereections, 2. Frequent urination or feeling I need to urinate, sensation is most prevalent in the evening time. 3. My penis at time is shrinking up inside me. 4. At times I have a feeling in my penis that is more like ticklish than itchy. 5. Sitting increases the feeling of need to urinate and times feels uncomfortable to sit.  Now I have not had any rash or bumps, no discharge that I can tell of. It does not hurt or burn when I pee. I have not had any fever or chills. Any advice from anybody. I am in a panic and my anxiety is wearing on me.

Anyone have any thoughts? Anxiety is killing me.

Prostatitis would cause 2 and 5 but I think you would be in more pain with that. I think this is most likely just anxiety.

Is there any particular reason you think you might have an STI right now?

If there is it's probabaley worth getting yourself screened. If there isn't my bet is on anxiety.

Prostatis is what I thought, and then read most were caused by sti. Which freaked me out more. 

About 2 weeks before I started having symptoms I went to an Asian message place and received manual mastrubation. Which should not pass on sti. But then I read we’re sti can have no symptoms for months, so maybe something from 5-6 months ago? I am not sure.

The itching/ tickling could be balanitis , easily treatable.

The erection problem could be age related , after 40 we start to lose our sexual vigor.