Symptom tracking lets you keep a journal of symptoms that you may be experiencing. You can track them for your own information or to help a doctor understand your health issues.
See a video here.
When you open the symptoms window, a list of symptoms is provided along the right edge of the window. If your symptom doesn't appear, you can use the 'other' item to record your symptom.
Note that symptoms are all available to be entered on your iPhone. It's a good idea to enter symptoms as soon as you notice them. Later when you are at your Mac you can download them to your Mac. Alternately, you can enter symptoms directly into the app.

You can use the app to make a symptom report at any time, again for your own use or for your doctor. Click on the "Make Report" button to open the window for making reports.
To enter a symptom, click on the symptom name on the right side of the window and then the "Add Symptom" button. A window like this will open;

From here, just select the level of the symptom that you are feeling. You can also add notes if you want. If the symptom was at a very specific time, click the "Specific Time" box or uncheck it if the feeling was over a period of time. The new entry will appear in the list of symptoms immediately;

If you are tracking a symptom over time, it is important to make entries even when the symptom is not happening. In that case just enter "Not Present". For example, if you are having dizziness, it is important for a doctor to know if it happens every day or if it comes and goes, so days where it is not happening, you should still make an entry.
Creating an Overview
To get a list of selected symptoms and selected measurements over any time period, first click the "Make Report" button. This window will open;

Select the symptoms and measurements that you want reported along the left side. Hold the "Command" key down to select as many items as you want. (See here for measurement entry instructions).
When you have the list that you want, select the date range you want to see and then click "View Summary". A summary will appear in the main part of the window. You can also click "Send in Email" and the report will automatically be copied to an email. You can enter your doctor's email or other caregiver and send them the report.