What's next?

Over the past month I've had two interactions with creepy old men.
The first one I was at a gas station in a busy area. There was a man being helped at the counter by someone and I was being helped by the other person behind the counter. I was asking a question when suddenly I felt a hand  full palm cover the entire left side of my butt and a slight squeeze.
I was so in shock and taken aback at what had just happened I was speechless. I looked toward the direction of the man and he winked and a smirk crept upon his face. Keep in mind this was at two o'clock in the after noon on a very busy Saturday. Throughout the rest of the day all I could feel was his hand on me. I scrubbed and scrubbed in the shower but the feeling would not subside.
After having previous incidents with a teacher years ago in middle school, it was everything I could do to not break down and cry.

The second one occurred yesterday. I was getting gas again, but at a less busy area here in Fairhaven. I was not physically affected this time, thank god. The man was paying for some items in front of me. As soon as he finished I quickly pre-paid for my gas. As I was walking out back to my car he held the door open for me, I responded with a polite "thank you" and a head nod. We both proceeded to our vehicles. I began pumping gas when an odd feeling crept upon me. I glanced over and noticed the man was in his truck staring.  Not glancing, but a dead stare. I held a stern look and made eye contact with him as he pulled out, waited at the red light, turned left and then he gave me the "up and down" a few times, finally some trees blocked our sight of each other.

I don't understand why this keeps happening. It's occurring more often then not. Others are more subtle then these two men but none the less, are still treating me like I'm a slab of meat and they're a hungry dog. It scares me to think about,  what's going to happen next? When? Where? What time of day?  Why? Is it something I did, or are you just a disgusting pig? Will someone go too far. It scares the shit out of me. But what can I do about it? Stay inside all the time and become a hermit? That's unhealthy. I shouldn't have to compromise my life because there are men on the prowl. That doesn't mean I'm out dressing like a street walker from the red light district. But I don't dress like a slob. I just don't know what to do. What to think.