IIH and POTS. Tachycardia syndrome?

I've suffered from severe headaches and heart palpitations since a year and half, recently for headaches I've been diagnosed for idiopathic intracranial hypertension, before this diagnosis, I've had very bad palpitations with resting heart rate 120+ and in afternoon even 140 with bad shortness of breath especially after eating. I've been put on diamox for headaches, I've relief from it but I've orthostatic headaches in afternoon, whenever I stand, I can feel my heart racing, the more it races, the more severe pulsating headaches I've. Are these headaches (orthostatic) related to IIH or postural orthostatic tachycardia syndrome? (Tho the nature of headaches is same throughout i.e. pulsating) Cause diamox don't seem to work on them.