Is this an infection or a stitch? (Photos)

I am almost 4 weeks post op TT and lipo a few days ago I had what looked like a pimple along the incision line, it has now developed into a small hole about 5mm big and there's yellowish fluid. It's not sore but I think it smells when I took the surgical tape off (it came away from the wound so I replaced). I have hay-fever at the moment, something I don't normally suffer from so not sure if what I think smelling is real or not. Overall I absolutely love my new shape and have recovered well.