Because you aren't looking after it properly.

Bumps are a sign it's irritated - are you washing it and applying ointment 3 times a day? You should be.

Itchy and clear fluids are nothing to worry about.

Infection is very red - burning sensation - red/yellow puss fluid leaking from it, if this happens, see a doc asap.

Could just be some irritation. I would suggest going to a doctor and getting it checked out.

If it was infected you would also notice extreme warmth, swelling and redness coming from your tattoo.