You are doing very well.
However, very strong students (which you are) get exposed to more difficult classes as you progress through your education. This means that you need to develop new study skills, and you also need to understand that you are going to get a B or two somewhere along the way. This is entirely okay.
You are going to need to learn to make sure that you understand the concepts, and you understand how to apply the concepts to problems, and you remember at least most of the more important formulae. In the past you just sort of did all of these things at once without thinking about it.
Relax. Have a pizza. Understand that you will need to learn how to work hard in difficult math and science classes. This is a normal part of growing as a student and every strong student has to go through it at some point.