New fit journey struggles

I started eating healthy and working out 2 weeks ago. I use to be in great shape but after a pregnancy and life with a baby and a full time job, not so much any more. I weigh the same as before baby but not as toned and fit.

I decided to commit to bettering my self before TTC baby #2. BUT, since starting I haven’t felt good. I keep getting headaches. I’ve tried increasing fluids and making sure I’m eating enough. It’s getting better the further into this journey I get. What do you think it is?