friends and relationships

So guyss....
Just wondering does anyone else kinda feel lonely or left out at times when people make plans and don't invite you, I mean even if you guys are not that close but still it kinda hurts somewhere.
Also, I moved school recently and my ex-friends from my previous school left me out and slowly limited contact with me. It hurts seeing insta posts of them laughing and having fun without me. We had all been friends for 7 years up to high school.
Please tell me if this is normal and what should I do. I often just begin to feel down seeing them having fun and i don't like being sad.