20 m baby was having minor chokes quite frequently last evening. Has been making funny breath sounds during sleep. Possibly rti or frn body or allegy?

See doctor. Foreign body ingestion pretty common in this age group. Other common things occur to cause abnormal breathing as well. If your baby isn't breathing right please take your baby to the doctor right away.
Needs X-ray. If this is something new then check it out with c hest x-ray. A 20 month will get their hands on anything then straight to the mouth.