Assuming touching by hand. This is a yes and no question. It depends if there is any opening on your fingers that come in contacts as well as if the female have STD to start off.
Also the duration and do you happen to "transfer" the fluid accidentally to other parts of your body...

1. Yes... of course, you may get. Transmission of fluid is achieve, not necessary need penetration.
2. You can make an appointment to check for STD 2 weeks after the incident and a follow up 3 months after that to be sure.

Good luck.

I'm no doctor so my advice may not be 100 percent correct. There are so many type of std..viral.. fungus.bacteria , besides std.hepatitis b is transmitted through body fluid as well. do refer first page and the saying that 'touch air it die' generally means that it is not air borne transmitted. The body fluid may have accidentally enter through your penis during that process of fondling.

But you don't need to be restless as well. First maybe she did not carry any std to start with. Second maybe the fluid quantity is too few to infect you. .

all in all.. Just proceed to Dr to get the best advice

You are worry because it comes unprepared... once you get it passes and clear... I believe you will go back in action in no time...
Anyway mate, no worries ok.... it is unlikely kena. If kena also, most STD in treat-able...
Remember to bring along "hat" next time and mind the expire date...

Again, I'm no Dr. but from the picture, it just seems like normal blister due to allergies or some insect bite on hand.
You should google some pic of STD.... make you want to puke
stay calm loo...