4 weeks post op Tummy Tuck, I am numb and have bubbles. Is this normal?

You're having pain when coughing and sneezing due to the muscle tightening. It is totally normal to have numbness of your skin after surgery. This will last for several months. Concerning the sensation of bubbling I would visit with your surgeon.  

you might find your symptoms unusual but all the things you are feeling sound normal, if you have any doubt you can ask your plastic surgeon, these feeling can go on for some more time so dont get nervous and keep on recovering. Good luck!

It sounds like you are recovering normally from your procedure. It is not unusual to have abdominal spasm and/or numbness after liposuction.i would recommend you follow up with your surgeon.

All of these symptoms sound normal to me. The numb feeling
will go away over time as the nerves grow back. A nerve only grows about 1
millimeter a day so it takes time for it to restore lost feeling (I would say 3
to 6 months). Sometimes the area directly under the bellybutton stays numb as
the area the bellybutton was brought out block the nerve from growing towards
the lower incision. The hypersensitivity will also get better. One technique
that help is to massage the area this seems to quiet down the nerves. If you
need further reassurance make an appointment to see your surgeon as I am sure
they will be happy to explain these symptoms.