So you shrink into a bundle of insecurity and embarrassment, and your academic progress stops cold. The first step in preventing, or treating this disease is to recognise that the condition is due to extreme self-consciousness, not to academic ineptitude. If you can convince yourself that there are probably other students in the class dying to ask what may appear to be stupid questions, then be a hero and ask on their behalf. Lecturers depend on student questions, especially elementary ones, to assist the learning process. Go and see your lecturer, often.
Most lecturers are sympathetic towards students who are trying to overcome their problems.
If you find your lecturer's attitude utterly unhelpful, go and see another lecturer in the same area or your course co-ordinator. Staff in Student Services are ready, and able, to help you with study skills programs and will lend a sympathetic ear. Make use of the services provided by the university and get your money's worth. Whatever you do, don't succumb to the Incredible Shrinking Disease. Since very few students possess an academic crystal ball, this is a particularly sad delusion that nearly always results in failure.