All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If the feeling of “difficulty in breath” and shedding tears are accompanied with fear of Allah due to reading the Quran, then this is a good form of submission, devoutness and there is no need for worry. Otherwise, it is from Satan; he resorts to such a way to keep you away from good relation with Allah and to place a distance between you and the Quran.
Thus, you are not to surrender to devilish plots and insinuations. Seek Allah's help faithfully, and this will help you to stop such devilish ways.
Allah Says (what means): {So when you recite the Qur'an, [first] seek refuge in Allah from Satan, the expelled [from His mercy]. Indeed, there is for him no authority over those who have believed and rely upon their Lord. His authority is only over those who take him as an ally and those who through him associate others with Allah.} [Quran 16: 98-100]
In addition, you have to keep on the confirmed Prophetic forms of Thikr (mention of Allah) in the morning, evening, at bedtime, when waking up, when leaving your home, and at all times and in all circumstances. Therefore, supplicate Allah earnestly to cure you; you can also seek advice from some scholars of the Islamic Centers in your country.
We ask Allah to grant you health urgently.
Allah knows best.