shooric,
If there is no pain and no discoloration I wonder if you are simply feeling the septum (where the two chambers of the tunica join). You will notice this a lot when you are stretching but it’s always been there and goes from the base to the glans.
There are no muscles in the penis (apart from tiny amounts of smooth muscle) and nothing that really goes half way up the penis. The suspensory ligaments wrap around the base of the penis.
So questions:
Is there any pain?
Is there any discoloration?
Is this a single thing or are there more than one?
When you feel it does it feel hard to the touch and with a certain irregularity or graininess (an indicator of thrombosis)?