down in the dumps

My hubby and I had a great day on Saturday , since I was feeling better and not exhausted as I have been . We did a lot of shopping for the baby . Well on Sunday I was exhausted so I took a long nap ..then yesterday I wasn't feeling all that great and slept the afternoon away ..I was certain that I would feel better today, but nope ..I still feel down in the dumps and I have lounged around all day and took a 2 hour nap. I don't want to do anything or go anywhere . I'm not sure why I'm so down in the dumps but it's making me upset because I haven't been able to do anything for the past 2 days . I tried going outside to get some fresh air , but it's scorching hot that made it worse . Anyone else feel this way while being pregnant ?