First of all, I am finding this post very disturbing. As an HR, and business management professional, I have been involved with various work places and situation my whole life, and while I have seen bullying, and hostile work places, this does not seem like a healthy situation for you or your co-workers.
1. I would speak to your provider about limiting or controlling your symptoms, including different medication. It sounds like you are have troubles functioning in the workplace and getting additional help would allow more productivity.
2. I would document the situations where they are mocking you. You have a right to a safe and harassment free environment. I would document the date and time of where then pen was thrown at you.
3. Do you have an advocate, coach or mental health professional? I would strongly recommend that you have someone to talk to, who can teach self advocacy, and other skills. In addition they may be able to assist you in developing appropriate accommodations
4. Does the company have a written anti-harassment policy in place? Generally speaking any company of any size would have some sort of handbook, and list of policies signed off by employees limiting harassment of any kind.
5. If you feel safe speak to HR, and I would even speak to the ownership. If you are experiencing bullying, hostility, and harassment in the workplace, then others are too. The ownership can be held responsible for their employees actions. In addition, it creates a very poor work environment which will cost them valuable, and highly productive employees.
As a side note, I really had troubles working with one person on my current job. She was to assist me in onboarding, and benefits administration. She rarely performed her duties accurately and completely. The paperwork was not completed, and we were not compliant with laws, rules, and regulations. In addition, other projects (in addition to HR, I oversee the accounting) and transactions were not handled properly. As I was about to file a grievance with my boss, the co-worker was offered another job, my boss encouraged her to move on. So whoever is the primary ringleader, may have numbered days.