What happened to my gum? (Photo)

Did a Dental implant 2.5months back and everything seem to be fine until recently. My implant tooth give off a foul smell causing my breath to smell bad. One side of my gum looks like it’s shrinking and a little swollen. There isn’t any discomfort except for the smell that’s giving off from that particular tooth. Due to I am pregnant now my dentist advice me to just gaggle with salt water as there’s nothing much beside antibiotic which could help.