I have a question

I will be having my 3rd (every 3 week) dose of Herceptin alone. After my first infusion I became dizzy/lightheaded a week after the infusion and it lasted until the 2nd infusion. I mentioned it to my oncologist at my second infusion and he said everything on my bloodworklooked normal, but that my blood pressure was low (106/40), my nurse ran a COMPLETE blood count and said everything was fine but, mentioned that she had never given the 3 week infusion and that I might want to try a 2 week one if the side effects were rough. I have my 3rd infusion tomorrow and since my 2nd infusion I have had periodic episodes where I will be at work (I'm an underwriter so other than arguing w/ agents, I have a minimal stress job) I get a feeling in the middle of my chest where someone has reached in and grabbed my breath (lasts a split second and won't happen for another day or 2). I'm also still lightheaded/fuzzy (dizzy wouldn't be accurate, but I feel like my head is floating). I know when I walk on my treadmill (I do 2 mi per day) when I begin my heart rate is 82, then at 1/2 a mile it is 135, then at 1 mile 78, 1 1/2 mi 120 and at 2 mi 81. I'm so nervous that my EF is dropping/dropped and that my onc will stop Herceptin. Has anyone else experienced this? Thank you.

Rhonda