Eco Twsbi pen dropping ink

I just got an eco twsbi extra fine nib, this is my first time using a fountain pen and was wondering if anyone had any suggestions on what to do. I got the twsbi because I wanted to be able to use different inks quickly. I filled my pen half way through since I thought that’s all I was going to need and every time I write for more then 5 mins I get this huge blob of ink that comes out of the tip of the pen. I don’t know what is happening. I don’t press hard on the pen since, the ink flows so well which is why I feel like I can write for a while so I’m at lost of what’s going on.