How to treat Sinus Tachycardia?!

I had Sinus tachycardia late December last year, fast heart rate 24/7 because my white cells in the blood were too high (fighting an unkown infection) and my red to low..the ones that carry oxygen in the blood. I had antibiotics which helped alot, I was at the stage i couldnt even stand for 2 seconds it was so bad and had to lay on the couch all day and 2 weeks off work. Now i am back at work, i have had my appt with a cardiologist who says its normal and isnt serious what i had, bloods came back normal at the doc's before my specialist appt. But my question is now...I still have the fast heart rate..not as bad - bearable but just annoying more than anything else....Ive noticed it's if i have fatty foods (heart speeds up trying to break down all the fat) , alcohol , caffiene, heat (sometimes have to have cold showers) and so on...Is there anything I can do to reduce this...I never had this before last December and the Cardiologist said after the antibiotics from the doctors I shouldve gone back to normal like it never happened. I know it sounds bad but it's really putting a dampening on my relationship cos I cant go out and do all the things i could before i get too tired and need to sit down all the time

Any thoughts would be great