If you are not thinking clearly and are starting to have suicidal thought creep into your head. Then you need to call your doc. asap. The fact that you are experiencing this with the sudden increase in dose. It looks like a possible med. issue. Another issue is how long you've been on sertraline. I'm sure you know that SSRI's can cause distorted thinking and suicidal thoughts in people. This usually takes place soon after a person starts the med and is more common in younger people, teens to early 20's.

Do not do anything irrational or harmful to yourself. If you have someone (friend, family, significant other) that you live with hang out with them. And talk to them about how you feel to whatever extent you need.

Regardless please call your doc. and do not be afraid to use his urgent/emergency number. This is the reason they have that #. You are under his/her care and they need to know whats going on with, the medication and treatment. This isn't something to put off or delay. Confusion and thoughts of harming yourself are not a good mix and you need to talk to your doc. immediately. If they do not call you back quickly, then call again. Also, talk to another mental health professional if you doc. does not call you back. There are numbers that you can call.

One last thing, if your doc/pdoc does not have an emergency number or does not respond. Then find another pdoc, that is basically malpractice and against the Hippocratic Oath that all physicians in every field must take.

http://en.wikipedia.org/wiki/Hippocratic_Oath