.....But I guess most probable factor in my case is hormones as I hit puberty 1-2 years earlier than my peers and since then I have acne.
You are not supposed to do anything in that case. Just try to ignore them and they will go away when your body adjusts. This is a normal response and even a doctor would advise you the same based on the intensity/symptoms. Diet changes will help but nothing will stop this permanently before time. Medicine etc are suggested only in extreme cases. This advise might seem stupid but two years down the line you'll be giving the same suggestion to your friends/peers.
Related to your first post.
Whenever someone mentions anything similar to "last day of the offer" or "last item left" etc I've conditioned myself to ignore it even if I feel like buying(impulse). This is purely a method to increase sales. Those phrases are meant to trigger impulse buying and this will happen even if you know about it. In your case this prevented you from checking other options like creating this thread.
Another negative point should have been the post-dated cheques. What kind of a doctor asks for post dated cheques. Even if I have scheduled multiple appointments eg. a dentist, the payment is done after the treatment and not before.
The agreement signing would be another negative point.
Trust your instincts, if anything feels wrong then don't do it. Instincts can be wrong sometimes as I've mentioned in the first point(impulse buying), that is how human brain is wired.