Give it a little more time and the tinnitus may settle down a bit. Glad to hear that your audio is normal. Really go over the spec sheet on the viagra (the pharmacist should have given you one) and see what all the side affects are.
I had a hearing test today. It showed no signs of hearing loss. The loud concert seems like the obvious culprit but the doctor didn't pay much attention to that once the hearing test came back normal. I've had several audio tests done in the past which they compared my results to so they are pretty certain the hearing is normal. Although Viagra isn't specifically noted as a cause, it is the one thing that is closest to the onset and I have had side effects like stuffy head and strange tastes in my mouth a few days after taking it. The Doctor was somewhat positive, saying if the hearing test was normal, there may be ways to deal with this. She has tinnitus too, so at least she knows what it is like.
Tinnitus can certainly be aggravated by a number of things. Medications can at times make the ringing sensation seem worse than others. I have heard that aspirin can sometimes create ringing. Aspirin and Viagra changes the characteristics of blood flow to certain areas of the body. This change could cause weird things to be experienced in the auditory system. However, it is a known fact that exposure to loud sounds in the environment over long periods of time can cause tinnitus. This is often times associated with high frequency hearing impairment. I would have your hearing tested. If you have a loss, hearing devices could help you hear better and help you cope with your tinnitus. As far as the time delay is concerned, I am sure that there is no concrete answer to this question.