Sometimes After Eating I Get Extremely Shakey And Feel Very

Sometimes after eating I get extremely shakey and feel very faint and like I'm going to throw up. This can happen several Times a week and sometimes I can go a few weeks with no problems. Although almost every time I eat I get very fatigued after a meal. It's been about a year with these issues and wondering if there is any specific tests I should ask to get checked out. What do you think these symptoms can be caused by?