Sticky stuff in lightning port

There is a sticky yellow substance in my lightning port. I’m not sure what it is, but I know it’s there because there was some sticky stuff around the charging port as well. When I try to charge, it tells me there’s a liquid in my lightning port and I can’t charge.

What do I do?

I’m on holiday so I won’t be home for another week or so and there’s apple store near me. Any way I can fix it myself?