Irregular heartbeat. My heart health?

Greetings sir/Madam I have an irregular heartbeat , even though not major changes in activities it keeps on changing between 80 to 100 in my mi band 5 , when I use my pulse oximeter to find the readings it constantly changing ( eg: from 90 to 100 and then down to 80 and then back to 95 like that) My heart beat in afternoon in high temperature after a small walk (less than 100m) and climbing a single floor goes upto 140 to 155 but takes time to come back to normal (atleast 15 mins) But My heart beat during morning brisk walk exercise goes upto 145 and comes back to normal in 5 minutes My resting heart rate as per mi band averages at 70 bpm I have gas trouble for past 1.5 months and discomfort in chest region after food , when lying straight . The chest discomfort resolves after a bleaching  . My tsh level 13.5 , hypothyroidism (not taking medicines) , my hdl 27 ,ldl 130, tgl 243 I have attached my ecg for reference Do I need to do any test to check my heart health?