That is ok. What you are experiencing is part of anxiety. What you have may be fear of illness, which can be hypochondria. It depends if this is your only fear or you have other fears as well.
You can face this fear by changing your thoughts. Use rationalization and thought changing. For example, when you have a thought about being ill, such as having cancer, think about it rationally. You have had these feelings for 8 years. Have you had cancer yet? Have you had any other illness you have been fearful of? Does your doctor say you are sick?
When you have these sensations, how often have you had them? Do they ever turn out to be actual illnesses? And if they did, so what? That is hard to think of for someone who fears illness, but it is necessary to face the fear. What if you did have cancer? Many people have cancer. It is hard to live your life without knowing someone who has had cancer. They handled it, and so would you. You can handle more than you believe you can. After all, you have handled anxiety for years now and you are still ok. Anxiety is no easy thing. It is hard and relentless to cope with. But you have done it. And you could handle anything else that happened to you too.
Try remembering that any symptoms you have are anxiety, and not an illness. They are physical symptoms, yes. But most physical symptoms are either fleeting, or they are caused by thinking certain thoughts, such as through anxiety. Very few physical symptoms turn out to be serious illnesses.
Also, remember to take deep breaths when you feel these feelings. It will help you associate relaxing with these thoughts instead of feeling keyed up and anxious. The more you can associate good things with these thoughts, the faster they will lose their power over you.
The tics you have can be related to control. They give you a focus and they provide a controlled movement in response to your out of control feelings. If your doctor has cleared you as having no medical reason for your tics, then they are related to your anxiety. Try the relaxation techniques and see if they help. You may be able to teach yourself to take a deep breath or flex your muscles rather than clear your throat.