So I've started walking more to help with anxiety. I've heard it helps and it has in the past. But lately I've been going for these walks and feeling worse afterwards.

 My heart pounds throughout the day. I feel lightheaded, and my thoughts race. 

I take 80mg prozac for anxiety and I started that dose in mid June. 

I'm just looking for some advice about this.
 Should I see my doctor or is there something I am doing wrong?