Sleep Disruptions and Health Concerns After Quitting Smoking - Cardiology

After quitting smoking, I experienced a relapse with episodes of waking up due to breathing cessation?

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I visited a doctor at the hospital who suggested that I might have hyperthyroidism because I experience heat and dizziness in the back of my head after being awake for 16 hours, making it difficult to lie down.
Additionally, I often feel a lot of heat in the back of my neck.
However, since I quit smoking, eat out infrequently, avoid bread, and have improved my daily routine, the heat has become much more manageable.
I also wear earplugs to avoid anxiety from dog barking, and since quitting smoking, I bought a thermometer to check my temperature when I feel heat in my head and neck, which only reads 36.1 degrees Celsius.
Although I no longer experience dizziness and the heat is now within an acceptable range, I still feel that the initial discomfort was more severe than just 36.1 degrees, but I did not record it at that time.
I notice that consuming salty foods definitely causes me to feel hot, and most processed foods lead to a similar reaction.
Eating out in moderation causes slight discomfort, but when I cook at home, such as boiling meat with a bit of sesame oil, I have no issues.
However, eating grilled salmon makes it difficult for me to sleep at night, possibly related to my emotional state before bed.
On days when I am awake for nearly 16 hours, I often experience multiple episodes of interrupted breathing while trying to sleep, leading to a racing heart.
I previously thought this was due to smoking too much, but I have not smoked for several days due to the dizziness and heat in the back of my head, and yet the symptoms have recurred, which worries me.
When I was close to quitting smoking, I only smoked one or two cigarettes a day, but now, after several days of not smoking, the symptoms have returned.
The only unusual thing I did that day was have grass jelly and garlic bread for dinner, which might be related to my low water intake of about 1.6 liters (I calculated that I only need 1.8 liters due to my slim build).
I haven't eaten out in a long time and have been cooking for myself because eating out clearly makes me uncomfortable.
Additionally, regarding my sleep, I usually take about an hour to fall asleep and often experience mental exhaustion before bed, relying on listening to bedtime stories to help me sleep.
I have also been trying to force myself to yawn through meditation, as I forgot how to yawn for about six months.
One day, after staying up for over a day, I could no longer feel sleepy.
Before my symptoms began, I loved eating salty popcorn, and when I felt hungry before bed, it made me uncomfortable.
Now, I can no longer eat processed foods; waking up after sleep leads to severe dizziness, and consuming them causes immediate heat in the back of my head.
Eating out causes a similar reaction, but it’s not as severe—just heat in the back of my head.
If I don’t force myself to sleep, I will keep waking up, but I managed to resolve this by listening to stories.
Initially, I would wake up after 3-4 hours of sleep, but after taking traditional Chinese medicine, I can now sleep for 7 hours (I read online that I need 8 hours of sleep for my age).
I used to be able to sleep for 9 hours, but my neighbors walking their dogs 24/7 made it difficult for me to fall asleep.
Since I started using earplugs recently, I have been able to sleep well.
Could this be cancer? I found online that these might be signs of cancer.

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Niming, 20~29 year old female. Ask Date: 2023/01/16