Ultherapy Dozens of Round Bumps Under my Skin on Checks, Jaw and Neck?

I can not comment on your condition as I am not examining you. I am only aware of rare cases in which there are welts, especially after use of the 1.5 mm. shallow transducer. Typically these fade in hours after treatment. Round blisters are not expected and could be caused by multiple different causes, some unrelated and coincidental with the Ultherapy.

The information provided in Dr. Shelton's answer is for educational purposes only and is not intended to constitute medical advice.  The information provided should not be relied upon as a substitute for consultations with a qualified health professional who may be familiar with your individual medical needs.

Blisters are fluid filled and not 'lumps'. Lumping is uncommon and I have never seen that after Ultherapy. It is related to not keeping the transducer perpendicular to the skin during treatments. It will go away. Recommend using topical neosporin. 

Blisters should not occur after an Ultherapy treatment. I recommend contacting your doctor for an evaluation if they do not go away within a few days or if any new bumps form.