Nursing 4 Times a Day

TL;DR version: My 4 month old has been refusing to nurse during the day for over a month. He latches on for a few seconds, then pulls away and cries. He is exclusively breastfed. I have tried many different things, but I can't figure out why this is happening or how to fix it.

Hello,

This is my first time posting, here, and I would be so grateful for any help or insight into the situation I am facing. I have browsed the other threads here and searched up and down google, and I haven't found anybody who has experienced quite the same thing with their baby. I apologize in advance because I know this post is way too long! I just want to make sure I fully explain the situation and all of the potential solutions I have tried without luck.
Some background info:
My son is 18 weeks old. He has been exclusively breastfed from day 1 without any issues whatsoever until he was about 3 months old. I have always fed him on demand, which up until 3 months, meant he nursed about 10-12 times/day.
His weight gain and diaper output were quite good from the beginning. His birth weight was 6lbs 15 oz. By 2 weeks old he weighed 8 lbs exactly, and at 6 weeks old he was exactly 10 lbs. Unfortunately, those are the only earlier weight measures I remember right now. Though he is physically healthy (to the best of our knowledge), he has never been the "easiest" baby in the world, and has always spent quite a bit of time each day fussing. He has a colicky sort of cry that is really intense and just seems to come on out of nowhere, and we haven't really seen any drastic improvements with this at 4 months old.

Cigar Register is an independent Windows-based desktop software, designed for cigar collectors. You can find information on cigars, manage your humidors, cigar collection, shopping history, wishlist and store your smoking history with your reviews. It can be downloaded for free from the official website.
Cigar DatabaseAn extensive searchable...

• Nursing t Test
• Nursing 1 Class
• Nursing 5 Tasks