As I'm sure you already know, you're suffering from a classic case of OCD - obsessive compulsive disorder - which we now know is a neurological, not a psychological condition (although it certainly has its psychological effects, as you have unfortunately seen from the way it impedes your mood, activities and relationships). It runs in families, usually hits people in young adulthood, waxes and wanes with neurohormones, and basically means that the little brain switch that automatically discards random worries as irrelevant, isn't operating properly, so the worry doesn't shut off. In fact, the worries and the rituals heighten in importance the more you give in to them. That's why it's so crucial for you to get the right kind of help, to break up this cycle.
Even though this may have been set off by the stomach virus, that's not what's driving this thing, and psychological insight won't make it go away. Any therapist who tells you otherwise is not properly trained to help you with this. (We've learned so much, so quickly about the neurological and biochemical basis of conditions like OCD and PTSD, that many of my colleagues haven't had a chance to catch up with the latest discoveries. You may have been treated by professionals still caught in this unfortunate time lag.)
What does work for this condition is a combination of Cognitive Behavioral Therapy, medication and, of course, since this is an anxiety-propelled disorder, relaxation and guided imagery.
You absolutely can learn to manage and control this thing, so that it's not running your life. You may not be able to get rid of it altogether (although you might), but you can absolutely, substantially reduce these symptoms and get comfortable with your life again. But you need to find the right kind of expert help. Behavioral therapy trains you to face these demons, a little bit at a time, and extinguish the anxiety in a controlled way.
At first the therapy can make you more anxious, because you're not giving in to your obsessions and compulsions, but it's presented and dosed in a way that you can handle, especially if you've gained some skill at using the imagery and relaxation techniques to help you handle the initial distress.
The sooner you tackle this, the better, because, if left on its own, the trajectory only gets worse and worse. So get cracking! Find an expert in OCD who uses this combination – I repeat: (1) CBT, (2) medication and (3) mind-body relaxation techniques.
Most teaching hospitals will have an anxiety clinic or panic disorder clinic. Some even provide residential care to help you over the hump if you feel you’ll need a lot of structure and support.
You can also get a treatment plan from a good book, such as Jonathan Grayson's Freedom from Obsessive-Compulsive Disorder: A Personalized Recovery Program for Living with Uncertainty.
Good luck and let me know how it goes.