Effects in the lung. Levodopa can cause disturbances in breathing function, although it may benefit patients who have upper airway obstruction.
umm.edu/health/medical/repo...
Respiratory dysfunction in Parkinson's disease.
Abstract
The parkinsonian syndromes include idiopathic Parkinson's disease, parkinsonian syndromes secondary to several known causative agents, and parkinsonian syndromes associated with more widespread CNS lesions and extensive neurologic deficits. They constitute movement disorders with a similar constellation of symptoms: rigidity, tremor, bradykinesia, gait impairment, and postural instability. All of the parkinsonian syndromes are associated with excess morbidity and mortality from respiratory causes, and all can produce the pattern of pulmonary function impairment consistent with neuromuscular disease. In addition, the parkinsonian syndromes can produce upper airway obstruction and abnormalities of ventilatory control, both of which can be life-threatening in those with MSA. The medications used to treat these disorders can also produce respiratory disease. A syndrome of L-dopa-induced respiratory dysfunction has been described, which may be a heterogeneic disorder of choreiform movements of the respiratory muscles, rigidity-akinesis of the respiratory muscles, or abnormal central control of ventilation, all related to the drug. In addition, the ergot-derived dopamine agonists can cause pleural and pulmonary fibrosis.
ncbi.nlm.nih.gov/pubmed/786...
Doctors tell me that I have paralyzed phrenic nerve effecting one lung, on my right side.
I had PFT-Pulmonary Function Test over one year ago. Last week I had another PFT and this test indicates my lung condition has declined.
What does the phrenic nerve do?
The phrenic nerve is a nerve that originates in the neck (C3-C5) and passes down between the lung and heart to reach the diaphragm. It is important for breathing, as it passes motor information to the diaphragm and receives sensory information from it.
Unilateral and bilateral diaphragm paralysis may be caused by motor neuron disease, myopathy, inflammatory myositis, phrenic nerve injury, viral infection, cervical spondylosis, malignancy (cancer), or may be idiopathic.
UNILATERAL PARALYSIS
Most patients with unilateral diaphragmatic paralysis are asymptomatic and require no treatment (image 1). The prognosis is good in this setting, and the paralysis is of little clinical relevance in the absence of new or underlying pulmonary disease
Promising results with electromagnetic therapy (reported long ago)
Is There a Parkinson's Disease Personality Type?
PD drugs accelerate disease progression 
Muhammad Ali and Young-Onset Idiopathic Parkinson Disease—The Missing Evidence
Do give homeopathy a go - you have a lot to gain and nothing to lose
