Aching feeling in shaft

I have had this aching feeling in my shaft for about a week. It only aches when it soft and it comes and goes. A few days before I did jerk, but I held in my ejaculation and was a little rough with it. I did have sex about a month ago. Can anyone tell me what's going on?

Can you explain the detail on this: " I held in my ejaculation and was a little rough with it. " ?
Do you wear tight clothing? Underwear, jeans, trousers that kind of thing …

I dont wear tight clothing. when I was jerking I squeezed my penis tight to hold the ejaculation in. While I was holding the ejaculation in, I was moving my penis a bit and was a little rough when doing it. I now have a pain on the left side close to the base and close to the head.

So when you have stuff like this going on time is usually the best healer.
The disruption or even damage you have done to the internals of your penis can take some time to heal - so we are talking weeks rather than days, and potentially months.
What may help is when you take a warm (never hot for your penis) shower use soft gentle movements of your penis, if you are familiar with massage, you are after gentle movements - leave completely alone if you get an erection.
Abstain from masturbation and sex until this is sorted.
The other thing you may have following the sex is a urinary tract infection in your urethra and this is where the sensation of pain is coming from - often drinking lots of water for 3 or 4 days can clear this. It is possible that you have both, an infection and internal damage, of course.
If the entire thing is not resolved after 4 to 5 months I would suggest you need to get checked out by a Urologist