A very depressing week 6!

So I starting training for my 5k in Oct. this week....I added in my walk/jog routine and also pilates, I then cranked up my elliptical with higher resistance levels. For my first week of training it went pretty well...no shin splints have come which is freakin awesome! This week I will be up to jogging a mile. Well not all at once that is. I do intervals of 10 min walk/2 min jog/10 walk/3 jog/10 walk/4 jog. Its kinda scary to run in public...I try to pick good times with not alot of people around. Anyways I had a 2.4 pound gain this week...so sad. I would like to think it was a mixture of gaining muscle and it being "that time of the month" but who really knows? I don't want to make excuses. All I know is that after all that work and seeing a gain is very sucky. Kinda makes me want to give in completely. BUT I plan on losing 5 pounds this week to make up for it. That means I must be very good! I am going away for the weekend too so I really have to do good! I can do it!