It's not uncommon for children to have a hard time with chaos.
Being a mom dealing with these specific issues...I will toss out what is a possibility and tell you just to use your instinct with this one.
Could be auditory processing problems. Where the child can hear but gets overwhelmed at the great amount of auditory stimuli that he gets all at once. How does he react when you go to an amusement park or to a busy grocery store? Any OTHER croweded place? Does he hate the sound of the vaccum cleaner or other sudden, loud noises? Like he comes unglued? If so, keep an eye out as he ages and learn about auditory processing issues.
Another possibility is Sensory Processing Disorder. These kids GET the sensory input but neurologically they are unable to process all of it properly. Your son is still young so seeing other symptoms may be hard..but watch as he grows for a strong dislike of certain textured foods or clothing, tags, maybe doesn't like how certain socks feel. Does he hate touching sand or rice or shaving foam or playdough..again, he's too young now but keep an eye out for these things as he ages.
I'm not trying to frighten you...but they are possibilities and if you google sensory processing disorder which is also known as sensory integration dysfunction, you can check the other symptoms to watch for. If you see any that really ring true to you, contact your area Early Intervention program to get an evaluation.
Tips, hints to get through the party?
ALWAYS keep your things together so that you can make a fast exit when he starts to get upset. Keep visits shorter...so go at the least chaotic time of the gathering and leave before the main insanity. That might mean coming FIRST and leaving before mealtime...because mealtime is always the most hectic. Lots of movement, conversation, noise noise noise.
Since he's young, you have the best excuse for heading out! He doesn't do well with long visits, it's time for naps, whatever....but you will be doing yourself AND that baby a great service by recognizing his limitations and working with them. Better to keep a visit short and sweet than to end with a stressed mom, very unhappy baby and family who wonders "why does that child cry ALL the time?".
You can also take nice little "walks" outside with him if the weather is nice. The rolling sensation can help calm him. Or if there is a way you can swing him slowly in your arms, swinging always helps my kids. Sometimes just holding him close, wrapped up firmly in your arms might help him to decompress.
Best of luck. ____@____.com if you need me!