Sudden feel chest sinks and heart stops.

My age is 24, (no alcohol and smoking addiction), sometimes I suddenly feel during walk or sometimes on sitting freely , I feel sudden my chest sinks or it's like my heart slowly slowly goes stop and my hands and legs get shivering or weakness like I lost control on my hands and leg , but after 1 minutes it gets normal and sometimes also feel symptoms like my breathing gets chocked suddenly for a second , i do reports like ECG✅,2D ECHO✅, ULTRASOUND✅, CHEST XRAY✅, CBC✅, LFT✅, RFT, THYROID✅, LIPID PROFILE✅, ELECTROLYTES TEST✅, ENDOSCOPY✅, HBSAG✅, HIV✅ all are normal , I consult with Govt Medical College CARDIOLOGIST Doctor (MBBS,MD,DM), 2 PULMONOLOGIST Doctor (MBBS MD)They says nothing too worry, please reply sir what actual happens to me , what actual problem I have please reply sir /mam , please 🥺