If you feel like you are going to have a heart attack, that is anxiety. Sweats can be anxiety as well. Stomach can hurt from Lithium or from Seroquel or from both or from anxiety. All of that can be written off as anxiety and does not present an urgent concern.

Tremor is a neurological side effect. It is not anxiety. It can be from Lithium or from Seroquel or from both. It has to be reported to the pdoc ASAP. If tremor is from Seroquel, there are antidote medications that may make it go away. If tremor is from Lithium, there are no antidote medications and you will need another mood stabilizer.

I will refrain from commenting on the practices of pdocs who prescribe two new strong medications simultaneously... There is the confounding effect (is it from med A or from B or from both?) that you are essentially dealing with.