My Daughter Says She Has Been Feeling Dizzy, Sick To

my daughter says she has been feeling dizzy, sick to her stomach, has no energy, has to sit down about every 20 minutes. she says the stomach thing is the worst, she feels she is going to throw up. she is 30 years old. sexual active with one person. has had an iud for 6 years for birth control. she said she has had her perod this month. she is very active she works out at a gym about 4 times a week and has 2 kids 6 and 8. she has good job and never gets sick. now thishas been going on for about 2 weeks. so she does not know what could be? do you have any suggestions?