We can;t diagnose you but your doctors have, and all is fine which supports their theory that it is just anxiety and headaches which many people get regularly and they don't get tumors. Anxiety makes you over-analyze your body looking for clues to the "symptoms" you feel. In your case headaches has coupled with anxiety to make you feel there is something wrong with your brain.
This fear and self-analysis has worked you up to the point you are examining the outside of your skull and feel there are dangerous swellings there. despite the fact your brain is on the inside. The soft brain can't swell through the skull which is made of bone.
The key to resolving your anxiety will be if you can accept the doctor's diagnosis, instead of trying to self-diagnose yourself. You have no medical training, and this is all they do so try to accept this. It may not be easy to give up your self-diagnosing habits with anxiety biting you and whispering false ideas that something must be wrong, but lots of people have once they realize it is just fear.
You are better off seeing a therapist than more medical doctors at this point, since your problem is that you are unwilling to accept what the experts have decided, and the therapist will work with you to resolve your fears, if possible. The fact you worried something would happen to your daughter initially when there was no reason, and the switch-over has now occurred (again with no reason) that you mention suggests this will be a good place for the therapist to discuss with you. (Or you on your own might be able to resolve this issue, if you can look objectively at it as you might be able to just shuck your fears since they have no base.) My relative is like that when she goes on vacation, always looking for what can go wrong with her adult family at home (her daughter went to NYC on business and she worried terrorists would blow her up, her husband was home during a snowstorm and she worried he would be driving in it, etc.) instead of focusing on the odds being in her favor that nothing is wrong.
Best of luck, and in summary a therapist might be able to resolve your issues if you go.