The symptoms you have described including: heart palpitations, shakiness, chest pains, feeling as though you have a lump in your throat, severe anxiety, and diarrhea seem consistent with a panic attack or panic disorder. Panic disorder is a type of anxiety disorder.
Another possibility is irritable bowel syndrome (IBS). IBS is a medical condition commonly associated with stress and anxiety. You also reported having a history of depression and possibly mania, a symptom of bipolar disorder.
It is difficult to provide an accurate diagnosis over the Internet. My recommendation is to have both a psychiatric evaluation and a medical evaluation. The latter is important to rule out the presence of physical health problems.
You have an appointment to see a doctor but you can’t be seen until July 15th. You did not specify which type of doctor you plan to see. If you would like to be seen sooner, call the doctor’s office and inform them of your concerns. You could also make an appointment with a different doctor. A different doctor might be able to better accommodate your needs.
I would also recommend making an appointment with a mental health professional. This could be with a psychiatrist or a therapist, or both. Psychiatrists can prescribe medication but therapists cannot. A therapist can provide talk therapy. If you have not tried talk therapy, you should. Medication alone is often not a comprehensive approach to treatment. In most cases, treatment for mental health disorders requires both therapy and medication. I hope this answer helps you to decide how best to proceed. I wish you the best of luck. Please take care.