Thank you for sharing what you are going through. Living with constant smoke coming into your home while dealing with allergies, skin irritation and other physical distress is difficult, and it is understandable that you would want relief and healing.
It is helpful to recognize the physical nature of what you are facing. Cigarette smoke is a real irritant to the body, and allergies and skin problems often have physical causes that need practical care. Scripture teaches that cleanliness and care for the body matter for health and for stopping the spread of irritation and disease. Healing is divine even when it comes through ordinary means, because God created our bodies with processes to heal and He works through doctors, good counsel, fresh air, cleanliness and wise steps to reduce exposure. I encourage you to continue to seek medical help for your symptoms and also to take practical steps where you can, such as speaking kindly with your neighbor about the smoke, speaking with your building manager about ways to limit the smoke entering your apartment, and caring for ventilation and cleanliness in your home.
The Bible does show that God heals. Matthew, writing by the Holy Spirit, applies the prophecy of Isaiah about the Servant who bore our sicknesses to the physical healings Jesus did when people were brought to Him, and when we remember the bread of communion as His body broken for us we are reminded that His suffering touches both our spiritual and physical need. At the same time, Scripture does not teach that God wills physical healing in every case in the way and timing we ask. Paul prayed three times for the thorn in the flesh, which he described as a messenger of Satan buffeting him, and the Lord did not remove it but gave grace to endure it. There is much about healing we do not understand, why some are healed quickly, some gradually, and some not as we hope. Only one gradual healing is recorded in the ministry of Jesus, but many healings happen gradually through the natural processes God established, and those are no less from Him. The wish expressed to Gaius that he would prosper and be in good health even as his soul prospers is a loving prayer, not a guarantee of health for every believer, though it does remind us there is a real connection between the health of our inner life and our physical well being, as a joyful heart is like good medicine and anxiety can harm the body.
For that reason I would not encourage you to view your neighbor as an instrument of the devil attacking you. The world is full of conflict between people, and Scripture warns that neighbors can speak without truth and deceive, yet Jesus also teaches that to love God and to love your neighbor as yourself sums up the law, and He answers the question who is my neighbor by pointing to the person in need and saying go and do likewise. Your neighbor is a person made in Gods image who may not realize the effect of the smoke, and the calling we have is to seek peace where possible, to speak truthfully and kindly, and to not assume evil intent where a practical problem exists. Spiritual opposition is real, but not every physical hardship is a direct spiritual attack through another person.
I will pray for you, that the Lord would bring relief from the smoke, give you wisdom for practical steps, comfort your heart, and bring healing according to His wise will. I pray that He would prosper your soul as you walk with Jesus, bring peace to your mind, and touch your body, whether through a sudden touch or through gradual and natural healing, and give you grace and peace in your home. I also pray that He would help you and your neighbor to live at peace, and that you would know His presence and care as you trust Him with both your spiritual and physical needs.