I read your symptoms and from my line of work (personal trainer) I know that the dizziness at 3pm is a very very common problem for many people - pregnant or otherwise due to a dip in their blood sugar levels. You should strongly look at trying to avoid pasta and bread at that time and instead arrange to eat LOW GI foods from morning till night which will regulate your blood sugar (therefore stop any insulin spikes) which will help avoid the 3pm problem. Pasta/Bread are high GI and are a quick fix yes, but what happens is your body absorbs the energy very quickly, burns it up quickly, then you go flat again after a short time. If you eat low gi foods you will have more constant energy levels and less dizziness.

Of course there could be other factors causing it, but as soon as I read your post it sounded like a GI issue with food. Hope that helps and gives you something to look into.

Best of luck!

ness