How do I treat excessive saliva after breast lift, lipo, and BBL?

I recommend you to talk about this with your board certified plastic surgeon to determine what's happening with your body. The breasts may lose their
elasticity and firmness which can be caused by different factors such as
pregnancy, massive weight loss, lactation and aging. To reaffirm the breasts
and restore the natural look your surgeon can perform a mastopexy or breast
lift. A breast lift restores a firmer, perkier, and more
aesthetically pleasing shape to sagging breasts. This not only can improve
a patient’s appearance by restoring her youthful, feminine proportions,
but also help bras and swimsuits fit more comfortably and attractively. By
removing excess, stretched out skin, reshaping the breast tissue, and raising
the nipple & areola into a more forward position, a cosmetic surgeon can create
a more youthful breast contour. Stretched, large areolae can also be
reduced during breast lift surgery, creating an overall better proportioned,
natural looking breast, Actually the perkiness on a person or another, depends
on patients skin and breast tissue for the first 3 to 4
months! 

Scopolamine can cause dry mouth. This may be a reaction to stopping the meds.  Best of luck.  Immediate concerns should be addressed by your surgeon.