My menstruation is 7-8 days and I shower sometimes at the end of the 7th day but on the 7th day I go to do a facial treatment where I can’t do ghusl or shower because my face treatment will turn into an infection. This means I will still not be tahir to fast the next day so I can’t do ghusl. Does it count as not fasting on purpose and I have to fast 2 months and pay fidya? because I can’t shower

by

If water will have negative effects for yourself then if it is not in the place of tayammum then you have to do ghusl jabeera which is cover the face with something and then wipe a wet hand over it. If it is in the place of tayammum then you have to do tayammum.

If you don't do ghusl and don't fast then yes it counts as not fasting on purpose