"further worsened" is correct and usable in written English.
You can use it to describe a situation that has been made worse or deteriorated. Example: The already bad economic situation further worsened during the pandemic.
The shortage of coal further worsened the electricity shortage.
The disparity has been further worsened by tax decreases for the top echelon of income earners.
Hughes's acceptance of the odd job of Poet Laureate has only further worsened his prospects as a live person.
Simultaneously, President Bush's disastrous foreign policy adventures, coupled with his blind faith in Mr. Putin, only further worsened the situation.
This disparity between wages and profits was further worsened by the fact that wages are taxed at a higher percentage than are dividends acquired from profits.
British-Boer relations in South Africa, always tense, were further worsened after the Jameson raid of December 1895, and, in October 1899, war began.
As US officials tried to make Karzai into something he wasn't – a competent, effective and popular leader – it led to more friction, which was further worsened by the increase in civilian casualties from the ramped up US war.
The increasing attractiveness of the city to the poor and less productive slows the process of depopulation but it reduces the odds that the city can stage a turnaround.In Detroit chronically bad government further worsened chances of a revival.
3 39 p.m. | Updated Simona Halep (ouster of No. 6 Li Na in the first round), further worsened the second round record (now 1-8) of players who pulled off major first round upsets at the U.S. Open recently, falling to 76th-ranked Carla Suarez Navarro in three sets Thursday.
By the time Zurbarán was in his 50s, Seville was suffering an economic crisis as a result of a diminution in trade with America and of the wars in Europe, further worsened by a plague in 1649, to which he lost his son Juan, a promising still-life painter.
The problem is further worsened by nutrient mining due to the low-input agriculture practices.
