Syntax: The structure 'Your love is like bad medicine' uses a simile construction with 'like' as the comparative word. 'Bad medicine is what I need' uses a cleft sentence structure for emphasis, placing the object 'bad medicine' at the beginning.
Morphology: 'Medicine' is a singular noun used as a mass noun in this context. 'Bad' functions as an adjective modifying 'medicine.' 'Need' is a present tense verb showing current state.

Syntax: 'There ain't no doctor' uses double negative construction common in informal speech, meaning 'there is no doctor.' 'That can cure my disease' is a relative clause modifying 'doctor.'
Morphology: 'Ain't' is a contraction of 'is not' or 'are not' used in informal contexts. 'Cure' is a base form verb following modal 'can.' 'Disease' is a singular countable noun.

Syntax: The structure uses parallel construction: 'First you need... Then you bleed... And then you're on your knees...' Each clause follows the same pattern for rhythmic effect. 'That's what you get for falling in love' is a result clause using 'what' as a relative pronoun.
Morphology: 'Bleed' is present tense verb, 'getting' is present participle form, 'falling' is gerund form used after preposition 'for.'

Syntax: 'I got a dirty down addiction' uses adjective-noun collocation. 'Like a monkey on my back' is a simile following the main clause. 'That doesn't leave a track' is a relative clause modifying 'addiction.'
Morphology: 'Got' is informal for 'have,' 'doesn't' is contraction of 'does not,' 'leaves' is third person singular present tense verb.

Syntax: Imperative structure 'Let's play doctor, baby' uses 'let's' for suggestion. 'Cure my disease' is an imperative clause following the suggestion. The comma separates the vocative 'baby' from the main clause.
Morphology: 'Play' is base form verb in imperative mood, 'cure' is base form verb in imperative mood, 'disease' is singular noun object.