Could I have multiple sclerosis?

I'm a 20 yr old female, and no I'm not a hypochondriac. A recent near collapse when walking down stairs due to my knee trembling caused me concern so I Googled it and found it could be a common symptom of MS. I thought nothing of, but decided to continue reading to satisfy my curiosity. I noticed how many symptoms I have that are related to the disease, such as: trouble focusing sight and seeing light spots, muscle fatigue, twitching, dull pain, discomfort, stiffness, and even itching (especially in my extremities), difficulty articulating and slightly slurred speech, balance difficulties and occasionally complete loss of balance when sitting down for a long period of time or exposed to heat such as a hot bath, frequent urination (8-12 times a day), dizziness and vertigo, depression, extreme mood changes (Bipolar disorder has been ruled out by my Psychiatrist), difficulty with short term memory loss and concentrating, and the phantom feeling of something caught in my throat. My symptoms become more frequent when I'm stressed and sometimes I go months without the symptoms in between stressed times. As far as I know, I don't have a family history of MS. I'm trying to decide if it could just be a coincidence or if I should schedule a Dr.'s appointment. I just started taking Zoloft a week ago, and besides a daily multivitamin, I'm not taking anything else.