My 4 mth old shih tzu is also infested with ticks, help?

Hi Meena, my personal experience says shampoos or any other anti tick product can kill only 60 percent of ticks at the most. The chances are 40 % ticks will still be there and will multiply in course of a week of so. Also, the more effective the product claims to be able to kill the ticks, the more toxic it is for the puppy. The chemicals can remove those natural oils from puppy coat that keeps the fur shining and smooth.
Having said above, I recommend you to manually remove the ticks from the coat using plucker. This requires a lot of care and patience but it ensure the ticks are removed from the coat and then killed. This manual tick removal process can then be supplemented by using an effective anti tick shampoo which can expose the ticks on the upper coat which then makes it easier to spot them and removed off.
Also, ticks make holes under the skin and then lay eggs
( resultant infection- Scabies ) so this essentiates the entire skin be disinfectened. Petcare's RIDD is one of these disinfectants . You must seek the vets advice about what quantity this medicine should be used.
Don't we humans like water in scorching heat?? Puppy tend to get overheated more than adult dogs so they use external environment to regulate their body temperature. If she lays down on wet floor, she may have small pimples which if catch bacteria can cause infection and itching. If that's the case, there are ointments available which can cure that.