Feeling Dizzy, Pinch In Heart, Racing. BP Ok. Healthy Eating Style. Suggestions

45 year old average/slim build, active male, i don't smoke or drink alcohol. past 6 months out of nowhere, usually at work, episodes of feeling like i'm going to faint, dizzy, lightheaded numb arms/legs, cold sweat and heart starts racing, sometimes a slight pinch in heart area then the dizzy and racing., leaves me feeling exhausted. usually happens morning-afternoon, a few times a week. Work day is spent mostly sitting at a desk until walking to the shops to buy lunch. I used to go jogging every morning for many years but due to change in circumstances not exercised half as much as i used to, could it be lack of circulation (i work in an office) drink 2 mugs of normal filter coffee in the morning, then either mint or caffeine free black tea during the day. I'm a vegetarian, but do try to get a lot of proteins through soya products, eat 2 thick slices of wholemeal bread with jam or chocolate spread for breakfast, 2-3 plain(no filling) wholemeal bagels for lunch and 1-2 apples, then a hot meal for dinner. I have to keep a large bottle of water beside me at night and consume 1 1/2 to 2 litres of water during that time. Doctor tested BP said it was ok, blood tests in a few weeks. Any suggestions?