Your body is dealing with too much stress, whether it is just the riding or a combination of factors is unknown. Factors like insufficient sleep, travel, family stress, money stress, etc. will all add to your overall load/stress and given the heat there recently, you could be dehydrated (doubtful but possible).
This is what I would do
1. Take 3-5 days rest. No cycling. Rest.
2. Really try to make sure you are hydrated
3. Resume training when HR resting is more normal. Start with some zone 2 easy rides and if RPE is normal, all is fine
4. In the future, monitor heart rate variability (HRV) to get an earlier warning to back off.
If the above does not restore balance, you could be sick. Losing 30W, 10 BPM increase in resting HR, and 4 kg lost weight are screaming......"REST"