Questions regarding STDs. My short story

Good evening folks, first off let me introduce myself. I'm a 26 year old, healthy, fit male that regularly goes to the gym to workout and exercise. I've also been sexually active with my girlfriend for 3 years and (now I'm ashamed to say, several other girls on the side. I know, I'm terrible, and I should be ashamed. I am).

Two weeks ago I had protected sex with four girls on different nights and wore condoms on every occasion except this for the morning after with this one girl who'd slept over (that night we had protected sex, but I ran out of condoms so the morning after I gave her about a minute of unprotected penetration before pulling out and immediately washing my penis. Outwardly she looked healthy, but she had a strong, pungent smell to her vagina which I think is worth noting and she doesn't seem to be the type to sleep around like a loose girl.

I'd also been staying up late, been tired the days prior and when I do this I usually fall ill with the cold or fever. Fast forward to Monday and I was starting to feel a bit under the weather. Then I got the stuffy nose, bit of a headache, and that "full" feeling in your head you get with clogged sinuses. Basically the symptoms of the common cold. It went away after a week, and it's been a week since I last had trouble breathing. I was freaking out the whole time, though, thinking I may have gotten HIV from that girl.
I've also been getting loose stools every now and then, but I attribute this to my anxiety over possibly getting infected with HIV as my tummy starts burbling whenever I get anxious but it's quiet when I'm relaxed.

Now here's where it gets yucky. Last week (I still had a bit of the colds then) my girlfriend and I had unprotected sex, and two days later she got an itchy throat, colds and a bit of a cough too, but hers subsided after three days and now we're back to normal. Now, one week after we had unprotected sex she tells me her vagina is itching.

Please help! I'm going nuts over here! Need advice ASAP!

PS
Yes, I will get tested, but right now I just want to know the possibilities of what I may have and may have passed on to my girlfriend.