Honestly, in your position, I'd just take the tramadol orally.
Tramadol IV is something I haven't heard much of, either in a medical or a recreational context.
I get it, I have shot up heroin literally thousands upon thousands of times, I loved shooting up. But.. Not ever drug is worth shooting up.
Because of tramadol unique properties, rapid onset is probably most dangerous than most opioids.
With that said, I agree that if you're gonna shoot pills you're gonna want a better filter. I always use cotton as well, but that's with heroin not pills.
If you're gonna do it with pills, a better filter is highly advised. Unfortunately I don't have enough experience to feel confident recommending a specific type.
What I will say, if you can't find this kinda stuff at say, needle exchanges in your area. You might be able to order them online. I've ordered syringes via ebay stores in the past. There's also some specific sites that deal in harm reduction materials.
Good luck.